This goes for the rest of 4chan, and the majority of social media as a whole, really.
Though the general becomes good/decent/informative/meaningful for a few days whenever we get a major content update. But after that? Yeah, it generally devolves back into shitposting/lewdposting.
Despite this I still prefer 4chan /lolg/ over other League-related social outlets like the LoL subreddit or official boards because people are allowed to be anonymous and post whatever the fuck they want. It's not some thought-police bullshit where people are forced or strongly encouraged to post "meaningful" content that contributes to an evergrowing hugbox hivemind mentality to retain their likes/karma status. You and your posts only get deleted/banned if you go full retard and post NSFW images/webms. And even then, the mods only do their job half of the time.