LinkedIn is mostly catering to the recruiters. If they make the job search too efficient then they'll stop being able to sell access to the candidates.

Drives me nuts too.

I mostly use LinkedIn as a place to curate my CV (resumé) and I reckon they'd be weak to a challenger who used that as their route into that market. Doubly so if they can figure out how to get the candidates to pay instead of the recruiters (there are more of us).