That turned me off, but at the same time, they do do the hardest part of the contracting/freelancing world - finding clients. If you're willing to jump through their hoops and accept a lower rate than you'd get on the open market, then it's a decent arrangement.
For clients they provide very good corporate customer service, and generally do a good job of screening people. My rate of "bad" contractors coming from Toptal is low and replacing them is quick. And every now and then you find some amazing devs.
Despite them pressuring you to put your rate as low as possible they still have a lot of room to negotiate with the client.
Me: OK, here.
Toptal: We're not taking on any more contractors right now, thanks for the data though.