Also I 100% guarantee that you are still trying to not get hit and stuff. Otherwise you would just play training mode.
We don't care if we get hit. I've had countless times where, for example, we're doing a Roy ditto, and we both so happen to pull out neutral B at the same time, and just let both fully charge just to see which hits first.
And if you think we are being super competitive with this, one person's favourite Samus combo is up-air to reverse back air (completely pointless, but that's the entire point). Another common combo is high percent Falcon dair to jab, and that's it (no follow up). Obviously we do more than just stupid stuff... but I'm trying to show how uncompetitive we are (suicide kills happen during 50% of all kills).
Obviously when we actually play properly, we're playing competitively... or at least trying to... but due to the huge skill gap, playing for fun completely non-competitively with nobody trying at all and everyone just playing for shenanigans reduces the skill gap, and everyone enjoys playing.
OTOH, I also agree that lots of 1p games have very little replay value. Super Mario Galaxy 1 and 2, for example. Both are really fun at first, but as you play on, it gets repetitive. And once you beat it... you've already beaten it, you've probably already memorized everything, nothing's a surprise, and... well, gg.