Because… drumroll….. 🥁…. The guy you get isn’t the one you see. The guy who shows up is certainly handsome/cute and skilled (if it is the same guy that I am thinking of) but just not the guy in the ad. So, this would cause very negative reviews on RM and here. Thus the blocking; this way you can’t leave bad feedback ( it has happened to me twice; with two different guys but same modus operandus. In one case the guy was hot and skilled so I wasn’t upset. In the other case he wasn’t ), which is a killer in this service niche.
The other reason to bait & switch is to hide your true identity ( maybe sees girls and this is a side gig ).