I'll have to disagree with you on this when you say "useless". Most sites don't post a salary, and for those few that do, a range is listed.

I like using https://angel.co/jobs to find those companies that have raised $ and currently hiring. One thing about is that I'm not really sure how frequently these startups have the time to update this on Angellist.

Not sure if I agree with that 100%. Not every job listing you find online is going to have salaries posted.

Not necessary for this sort of ads.

What sites list salaries?