It is so bad that is makes me suspect it's by design. Just like 419 scams evolved to be ridden with errors because that efficiently filters out non-scammable people and captures the prime slice of the most gullible, maybe these are designed to capture only the most desperate and unselective.
A second theory of mine: by being vague, the recruiter can hide the fact that they have maybe 10 different roles with nearly the same description. Get my ear and they can probe which I’m best for and try to sell me that.
This doesn’t explain why someone would use these recruiters though. As an employer I’d insist that even for a $1k recruitment fee, the contacts weren’t actively scaring off any reasonable devs. Remember I’m not asking for “personalized” - I’m just asking for “minimum job parameters up front”. To recruit a decent dev, this shouldn’t be a cost at all.