Responding with “Yeah, nah.” or a more formal equivalent is hardly going out of your way to operate with integrity in a manner that will get you massively fucked.

Yes, ghost those who don't take “sorry, but no” (or more succinctly just “no”) for an answer, especially those who have done so repeatedly (those are a time sink and deserve ghosting), but I wouldn't take it as my default position. Try not to become what you hate.

OK, so I tell a bit of a lie: ignorance is my default and only response wrt LinkedIn these days. I see the “you have messages/requests / people are looking at you” alerts regularly by mail, but I've not logged into the site in half a decade or more which anyone looking at my profile (rather than just being a gattling-gun invite spammer or similar) could probably tell with ease (the fact they bother contacting me is a good indication that they aren't a useful lead!).

My experience is that operating with integrity in a domain where nobody else is gives you a tremendous advantage over "the competition" and can be self-protective.

Interpersonal enshittification's cause in a nutshell.