Why modern anime struggles with "overanimation" so much?

And yes, it's absolutely a real thing. Read about "principles of animation", they basically tell you things like "a fast movement should be less frames" or "use more frames to make a slower movement" etc.

It's why shit like "4K AI upscaled interpolated frames" anime looks like garbage.

It looks like modern Japanese animators are utterly clueless novices when it comes to this shit and lack any theory.