>>280371441
>This started changing around the mid to late 2010s
They've been around a lot longer than that, it's just that position which is now occupied by mainstream shounenshit used to be held by the sort now pushed further into the periphery that's lucky to get 12 episodes at all. Mahoromatic, Ikkitousen, Nanoha, GitS SAC, Raildex, School Rumble, SZS, Minami-ke, etc. Anime originals have especially suffered, from obscure stuff like Godannar and Divergence Eve to ones as mainstream as Gundam which started with multiple 4-cour seasons to 2 2-cour seasons to 2 1-cour seasons and the latest was a 1-cour 1-and-done.

While at a glance, it looks as if the quality of the mainstream series indicates better resource management by the industry, as you say yourself there's plenty of filler (and those mainstream series aren't that much better anyways--or a new phenomenon, as boutique studios like Madhouse and Ghibli have been around since before the real estate bubble). Rather, good human capital is becoming increasingly scarce while total industry resources balloon and the organization thereof worsens due to dependence on Twitter for networking. They simply can't afford to run a series year round anymore, and with those same limitations comes the risk aversion that has strangled creative expression across the entire totem pole.