The author is talking about the case where you have coherent commits, probably from multiple PRs/merges, that get merged into a main branch as a single commit.
Yeah, I can imagine it being annoying that sqashing in that case wipes the author attribution, when not everybody is doing PRs against the main branch.
However, calling all squash-merge workflows "stupid" without any nuance.. well that's "stupid" :)
I think the point is that if you have to squash, the PR-maker was already gitting wrong. They should have "squashed" on their end to one or more smaller, logically coherent commits, and then submitted that result.
I don't think there's much nuance in the "I don't know --first-parent exists" workflow. Yes, you may sometimes squash-merge a contribution coming from someone who can't use git well when you realize that it will just be simpler for everyone to do that than to demand them to clean their stuff up, but that's pretty much the only time you actually have a good reason to do that.