A big part of their sequels bellyflopping is due to the management deliberately ignoring what their customers want, and instead making a game that undermines the previous entries popular components in an effort to trick the audience into liking what the studio heads and execs want.
Uncharted 2, 3 and 4 weren't flops. Hell, even Lost Legacy performed great for a smaller title. The same is true with the sequels to Little Big Planet, God of War (including the reboot) Infamous, and even games like The Last Guardian, thematically following up on the studios previous stand alone games.
Meanwhile we know TLOU2 deliberately killed off Joel and forced us to play as a bunch of woke loonies because the team at Naughty Dog didn't like how people felt Joel was a hero, and wanted to subvert expectations. Spiderman 2's devs knew people hated playing as Mary Jane and didn't want any of the far left political themes, but they forced more in so as to try to brainwash them into liking them. There were an enormous number of criticisms of Horizon 1, focusing too much on story and characters and not enough on gameplay variety, and all of that was ignored and the game made even duller and more Californian soap opera like in 2.
For a couple of generations Playstation had the right balance between making good sequels and not letting franchises turn stagnant. That gave them an advantage over both Xbox and Nintendo, and is likely what spurred team Red to try more new IP's like Splatoon, and reinvent others like with BOTW.
Now though they're making the same mistakes as all the other elitist, over educated and over feminised western entertainment company, and are just making products for themselves as a way to vent their frustrations and anger into the world.