Some companies don't hire _except_ through recruiters, and sometimes only through a particular recruiter. There may be, er, commercial relationships of which you are not aware, or just a comfort level, or more common now, the company's HR department comprises one overworked person who outsources pretty much everything.
A good recruiter will only present you for a job for which you're well matched, may coach you a little on things like what to not brag about, and may do a little selling on your behalf.
A bad recruiter will try to hammer you into any open hole, regardless of the actual fit.
There's no way to tell the difference until the process begins. Some big outfits are staffed entirely by 'bad recruiters'. Some big outfits have some local offices staffed by 'good recruiters', and some not so good. You have to feel your way around, and keep your own list.
Listings on company websites often lead you into third party "resume generators" that mostly manage to present you in the worst possible way, and probably to the worst possible decision maker, that overworked HR minion.
IMHO, even if you can identify the company, you're probably better off with a good recruiter.
Don't do both, i.e. talk to a recruiter _and_ apply directly for the same position. Recruiters talk to each other, and it may not make a good impression on the hiring manager either.
Mike Halloran
Pembroke Pines, FL, USA