Why is this dude the most hated Simpsons writer ever?

He created the most cancerous meme in recent memory

Burns, Baby Burns B
The City of New York vs. Homer Simpson B
The Trouble With Trillions B-
Trash of the Titans C
Lisa Gets an A B+
E-I-E-I-(Annoyed Grunt) B-
Alone Again, Natura-Diddily B
Tennis the Menace D+
The Blunder Years C+
Large Marge B-
Dude, Where's My Ranch B
Catch 'em If You Can D-
The Heartbroke Kid B

i hate john Swaltzwalder

mostly because he promised to paint my fence 40 years ago

Not the worst writer but unpredictable as fuck and seeing his name on an episode is always worrisome.

>Large Marge: Bad concept, the story progression was okay.
That's actually my favorite one out of all of them. The song is hilarious and some of the problems Marge faced I felt were pretty realistic (as far as the Simpsons can be). Also, it made Homer lovable again instead of just plain dumb.

IMG is just another name on the list. I don't hate him, don't love him.

Burns, Baby Burns: Larry was pretty funny and the pacing and jokes were decent.
The City of New York vs. Homer Simpson: A bit overrated but not at all bad. The musical number is great, as is Homer's flashback, and the side-by-side plots work well together. Homer needing a bathroom was a simple joke, but in this case I thought it worked.
The Trouble With Trillions: Wacky as fuck although some of the jokes were ok, the first act is not very related to the rest of the episode and the resolution felt empty.
Trash of the Titans: Homer is way too much of a jackass, Steve Martin and U2 are wasted, and the ending is a total cop-out.
Lisa Gets an A: Not bad but somewhat overrated. Lisa's plot seems mundane and stale until she becomes addicted to video games, the Homer subplot isn't very interesting, and Nelson's story feels like a retread of Bart the Mother.
E-I-E-I-(Annoyed Grunt): A typically Season 11 SMC-tier episode with anthro animals, a bizarre Homer gets a new job plot, and the usual first act that has nothing to do with the second and third acts antics.
Alone Again, Natura-Diddily: Fucking disgusting on all counts from Maude's death to Marge giving birth to Flanders' dick, its simplistic conclusion, and its decision to get Ned dating in the same episode that his wife got killed in, this episode is horrible all around.
Tennis the Menace: As usual unrelated first act and bland all-around. The story is predictable as fuck and the celebrity cameos are useless.
The Blunder Years: The plot doesn't get anywhere near interesting until the flashback, and even then the humor is still more or less regular barring some needlessly drawn-out jokes about Moe. The prank played on Marge and Homer screaming uncontrollably seem to take far too much time away from the plot, and neither plot point is all that humorous either.

Large Marge:The premise for the main plot just feels weak overall, and the subplot seems stale and reused from Itchy and Scratchy and Marge. The song also seems out of place, and the resolution was a pretty lousy use of imagination. Though there are some occasional laughs (like the Batman TV show) I just find this episode forgettable.
Dude Where's My Ranch: Yet another throwaway first act that just serves as a vehicle to get them to the ranch and Homer's song about Flanders which just feels too mean-spirited to be funny (speaking of which, Moe's season 14 creepiness is in full force with that joke about Misery). The dude ranch subplot with Homer and Bart is forgettable, and while the main plot is okay, Lisa's characterization seems off as she acts kind of irrational overall.
Catch 'Em if You Can: I hate this episode so much, it's probably one of my most hated episodes. Everyone is in full force jackass mode and the subplot with Grampa is completely interesting. To top it all off, the final act uses another overworked plot device, the gratuitous life-threatening situation climax which wraps up with Bart and Lisa watching their parents fucking.
The Heartbroke Kid: There's some pretty good direction in this episode, and the plot plays out in a creative way, but there's not much else I like about it. The jokes feel so long and drawn out what with the Itchy and Scratchy cartoon, the parody of the opening sequence, and the many lines given to Albert Brooks' character, making everything move so slowly.

I don't understand he is often labeled as a person responsible for the decline. If we go by writing credtis, John Swartzwelder's record during Seasons 10-12 will label him as the worst writer of the period but that certainly isn't the case.

But he is quite an uneven writer. I feel many of his episodes tend to ignore characterizations and plot and rely on gags to make the episode good. Sadly the gags are often very hit or miss. However, two of his episodes that I find best actually had good characterizations so maybe he has the wrong priorities.

From the episodes posted in here, he comes off pretty poorly. For instance, every real moron that I know absolutely loves the Tomacco episode and would probably rate it in their top five if they could count that high. And I’m not saying that anyone who likes that episode is an idiot, but from what I’ve seen it generally caters to the low IQ crowd. And I always thought TCONYVHS was overrated. It had a couple of decent gags, but considering when it aired, it's pretty poor overall.

I watched Dude Where's My Ranch in syndication the other day so its awfulness is fresh in my memory. As usual, unrelated first act to the rest of the episode, the Flanders song was mean-spirited, un-called-for and in many ways seemed to be a device to take vague jabs at certain viewpoints (like the lyric, "his views on birth control are wrong"--is that supposed to be funny, or just to voice the writer's beliefs?) The main story is not much better. Are we really supposed to root for Lisa here? If so, why? And if not, why would we care what happens? Also why does a 13 year old want to hang out with/date an 8 year old? The jokes are very in-your-face and stupid (Maggie Britney Spears parody, Marge hiding behind the cactus--these things are very obviously trying to be funny and very thoroughly failing). The subplot is just another excuse for Homer to act like an idiot/be in pain. And when a character says something so utterly retarded as "our animal equals," it just makes me shake my head in disbelief. It’s such a failure of an episode that I’d like to have it erased from my memory if that's ever feasible in the future.

Overall, I’d say this guy is pretty bad, but not intrinsically worse than most current writers on the show.

Reminder that he got into a fistfight with Norm MacDonald at the SNL studio.

>Graham walked into the writers' room backstage and saw MacDonald puffing away on a cigarette and dropping the ashes into a Coke can. He was carrying a bottle of water which he proceeded to spill all over MacDonald's head. MacDonald immediately punched him in the face and the two started into a scuffle that culminated in the nearly 7 foot tall Graham pinning him to the ground. He wanted MacDonald arrested and charged with assault and battery for punching him, and for SNL to be more serious about enforcing their no-smoking policy.