Nothing to do with LinkedIn. I write like that online because I feel people read like that online - they more easily consume bullet point style writing than paragraphs. Dunno if that is true or not.

I think of it more as a BBC thing than a LinkedIn thing: https://danielmiessler.com/blog/email-like-bbc/

If you're trying to get your point across to busy people, short paragraphs help.

I think you're right, but I also think it loses its punch if you overuse it. I'd suggest saving it for lines you really want to highlight.

It's called broetry.

It's become a thing over the past few months if not longer. People tell their stories in the sentence per paragraph form, thinking it adds drama, I guess. I find it a bit annoying.