Almost everywhere I applied, and these are dozens of positions over many years, I wrote a concise, sometimes funny, sometimes provocative, sometimes insightful cover letter. If I knew something about the company that HR would find interesting, I would write it. If I knew something about the industry or the founders, I'd mention that as well.

My personal experience is that cover letters do not help at all. At best, it's a test for myself. If I don't want to write a cover letter, I should not apply.