The biggest problem I have with them is their incentives are misaligned with what you want. A recruiter doesn't make their money by getting you the best offer. They make their money by helping sign a lot of people. Which is why they always ask the salary question. So they can build a rolodex sorted by salary ranges and then experience levels. In fact, there is probably algorithms for prioritising the placement of the most qualified people asking for the least amount of money.
I would almost be worried about new comers in tech who maybe haven't dealt with recruiters before as recruiters are VERY good at extracting personal information. In any other field what they are doing would be illegal. In fact in information security you would call it social engineering. But people in recruiting just call it their job.
It's even worse when you consider that this is a part of the process when people might be more vulnerable or desperate. Perhaps ironically the old work-from-home-fake-job-offer-scammery-roo is also used by identity thieves, doxers, and fraudsters for the same purpose and really: Is there much difference between that and recruiting? Both of them sell a lie to extract profit from the person they target and the means they do so is extremely similar.