In the time it takes me to read an article about daesh or whatever someone else could easily upvote thirty memes, make five, and repost twenty. It doesn't really matter what the majority wants, single images and image macros are so easy to consume that even a tiny minority liking them can quickly overwhelm any sub that doesn't ban them outright.

If two people are reading an article while one person rifles through a bunch of image macros and gives them each an upvote, by the time they finish the article their two votes will still outweigh all those dank memes.

You've been here more than four years, I'm certain you've seen at least one personal favorite double or triple in size and take a sharp drop in quality. /r/atheism originally had a lot of articles about politics and con issues, then one mod who liked memes turned it into advice animals for 14 year olds who love to brag, so people moved to /r/trueatheism which turned to shit and so on.

Unless that mod was actively removing non advice animal submissions, I can't see how that was possibly his fault.

It's happened every single time the mods don't get aggressive. /r/ askreddit and 'what's the sexiest sex you ever sexed?', /r/gaming and 'DAE remember mario???", /r/books and 'I know it's already on the front page twice but let's talk about lord of the rings!', /r/funny totally losing text posts and jokes and becoming advice animals for a long time, /r/technology and the constant struggle to have more posts about technology than about who someone who doesn't develop original technology might have fucked. . . the only way to keep a sub focused and filter for high quality is to be like /r/askscience and instantly ban everything even a little off topic.

And if the majority agreed with your opinion on high quality, moderation wouldn't be necessary.