Fair enough. But there is some speculation at https://torrentfreak.com/nintendo-m...s-hundreds-of-fangames-from-game-jolt-210105/ that the inclusion of ads was problematic.
But I will readily admit it is pointless to speculate - and people will speculate anyway, and say "WTF is Nintendo doing?", and yet other people will keep buying Nintendo's products. Because really, I'd never heard of gamejolt.com until now, and the vast majority of Nintendo's consumers probably haven't either.
Money does make lawyers perk up -- most courts are not fans of doing things on principle when it comes to business, and any good lawyer will tell you if the likely amount you will collect will be less than fees or be unable to collect (win a million against me and you will never get close to that actually paid out by me as I don't have it).
However the nature of trademark law means you can't really stand for flagrant abuse going wide. Their consumers not hearing about it/knowing about it means little vs their consumers (which does include little old ladies buying games for their kids and grandkids) potentially being confused.
Their alexa ranking is also not bad for online games either and that would likely count more than self selected types on a site like this (in many ways they rate above newgrounds).