Earlier quoted context omitted.
ML researchers saying they need "category theory" sounds like a way to try to convince mathematicians that their work is cool. You absolutely do not need category theory. Math is just models? Lol!
The parent didn't say category theory is necessary to conducting ML research, just that it could be useful. This point isn't particularly controversial. If you're interested in this niche of the field, I find Tai-Danae Bradley's work to be pretty cool! She has a site: https://www.math3ma.com/
What do you mean that "this point isn't particularly controversial?" If you just mean that "X may be useful", then of course. But the particular X matters, and "could be useful" is much different than "is useful".
People who like category theory want it everywhere. I don't know your mathematical background, but spend any time in a math department, or even classes, and you'll find people ready to explain any topic in the language of CT.
The may be useful, but it has to be justified. It's clear in some mathematical contexts, but definitely not in ML (yet alone analysis).
ML has a problem in that no one knows what certain methods work. Just look at something like batch normalization: I can think of at least 3 different "explanations" on why it works.
ML people want explanations, and mathematicians need work. Category theorists therefore have work. But I don't think you should mistake this as being an explanation. You just get a nice get a "cleaner way" to present concepts.