When people say “Smash isn't a fighting game”, I take that as a compliment. Fuck 99% of all fighting games, because Smash is better than all of them. All fighting games play basically the same. You pick two human or near human characters out if a small cast if characters who all basically have the same moveset with minor statistical differences, it doesn't matter, because they're all fucking clones of each other. You then take your two samey characters to a stage. It's the same stage in every fighting game, a flat two dimensional plane that you circle on until one of you gets bored and engages the other. At that point, the winner is wholly decided on who mashes the right buttons (block, attack, block, attack, block, block, super)
Compare this to Smash. The whole roster of characters is wildly different, and many aren't even human. And each of them plays radically different, with wholly different movesets that relate to their lore and appearance. Mario, Kirby, DK, etc., All have wildly different movesets and movement styles. Did I mention movement? Yeah, that's important in Smash. Turns out, their are actually dozens of different maps which, like the dozens of unique characters, are all individual with their own characteristics. Some characters move around better on certain maps, and players can use this to their advantage. Some characters are fast, some are slow, some are heavy, some are floaty. And because of Smashs unique, although often copied KO system, matches aren't always decided by lowering an arbitrary bar to 0.
Do I need to go on about Smash's variety of different features that also make it an amazing party game, in addition to the best fighting series on the planet? No. Because at it's core, even if you stripped all that shit away, Smash has more depth and requires more skill than any other fighter on the market. I'm glad Smash is ‘not a fighting game’. Fighting games fucking suck, Smash is the GOAT.