> But mostly, when people say "cops suck" they're talking about the institution

Dehumanizing groups of people isn't constructive. Telling someone they suck, chanting "fry them like bacon" at protests, etc then pretending that it isn't personal is disingenuous at best.

It's not a fair comparison to say "don't stereotype" as though race/religion/ gender is an equivalent category as an organized team of professionals who join up together for a common purpose in not just in one way but two (the force itself, and then again the union)

"Cops" isn't an organization, or an institution, they are people.

Insulting people, pretending it is a criticism of an institution, then replying with a pithy "dont take it personally" is dehumanization. That would be like saying "professors suck" then insisting that no, you aren't insulting professors, you are criticising the academia. It's intellectually dishonest. It is pretending that professors aren't people, they are nothing more than a representation of a synthetic power structure.