That implies most of these people actually -watch- cartoons beyond Steven Universe. Like, if they did, they'd know that Sonic Boom has been premiering on the re-run network for the best part of a year now; and so have episodes of some other shows, so it's hardly a new or shocking thing. The decay of boomerang is sad, especially given how much of TTG's hatred seems to be based entirely on it "replacing" the original. Maybe, just maybe, Boomerang could include older CN shows like Teen Titans in its catalogue had it not been completely bastardized years ago.
Anyway, all the salt towards Teen Titans Go is stupid. It's an inoffensive comedy show, and it's super popular with kids. Of course it's gonna oversaturate a network when CN's biggest competition, Nickelodeon, has similar schedule oversaturation for their most popular cartoon, SpongeBob - an inoffensive comedy show that's super popular with kids. And, well, Nick can survive off of SpongeBob licensing and merch money, so clearly it's a model that works. It's almost like companies, especially ones that have been struggling, like a proven money-maker.