A really good video on the subject: https://youtu.be/_KRb_qV9P4g?si=x0pmLkBhLYXud4G0
The gist is that, for animation, frame interpolation messes with intended timing and can produce incoherent images on interpolated frames and odd frame rate issues for certain kinds of animations. Interpolation can thus cause animations to lose their punch and feel wrong.
While interpolation may be nice for live action films, it should still be an option to turn off.
He only talks about animation, and even then it's a specific software and method that does a really bad job. It's a strawman argument.