I also wonder why as well as I always get this treatment from recruiters on LinkedIn (they give very vague descriptions about the job, no mentions about the salary)

The worst part is they insist on getting my phone number to call me even after I told them that I would only to talk them via Google Meet/Teams/Zoom..
(the recruiter ignored my request and emailed me her phone number for me to call her instead.. in the end I ignored her cuz I've checked her agency's website for those positions she shared and they don't interest me)