Playing to win isn't always fun, what if playing as sonic is fun to you, and playing metaknight isn't? Doesn't matter how fun winning is if you do it with a character you don't like. People tend to cite Sirlin when they don't have a decent argument of their own, not to say I don't think you do, but people throw it around so much that it's a cliche and has lost a lot of it's meaning.
There are also lots of ways to do both to an extent, I play 4 characters, Pikachu, Ike, Sonic, and D3. Pikachu is my high tier fun character that can win most high skill high difficulty matches, Ike is my team tournament beast, plus team tournies are just fun and help keep me playing the game. Sonic is my mid low tier fun character, if someone is less skilled than me I can generally stomp them and have fun doing it with sonic. Finally, D3 is my "metabuster", The only way I play D3 is anti-metaknight, I know it's a negative matchup, but the way I play him, and my experience in the match up makes up for it.
I don't play metaknight, not because I think it's cheap, but I do think it's an easier way out, and it takes away from my other characters to use him. Am I going to lose more because I don't main meta exclusively? Yeah, is that playing to win? No, but it's definitely not "items on everyone wins" either. In my scene I'm one of the top players despite the obstacles I've set for myself by not playing metaknight, and I'm okay with it, I don't need to hide behind "play to win" to justify anything I do, and I still win, which is plenty good enough for me. I really don't think people that play like me deserve any criticism for it either, we're not neccesarily less skilled players, (it takes more skill to win with a lower tier), and unless we start spouting off with "you just won cause you play metaknight" or " you're just cheap and use glitches to win" I really don't think we should get flack for anything.
I'm fine with not dropping my characters/playstyle to win more often, and I'm a far cry from being a noob, so I really don't think that should be a hinging point of this argument, or even an emphasized one.