An established provider like Analeese doesn't have to worry about losing business by implementing a no-review policy. She already has a lot of great reviews, is known to provide a very pleasant experience, and knows how to promote herself effectively by posting in Coed, Sandbox etc. Same is true for the other established providers who have posted in this thread.
However for providers who are not at that elite established level, implementing a no-review policy will most likely hurt their business. I communicate with lots of other guys on ECCIE, mostly through private message, and the number one topic we discuss is reviews. Just like you ladies screen us guys, we screen you ladies too and our most important tool at our disposal are reviews aka encounter reports. Reviews for us men are like references for you ladies.
Especially recent reviews because people change with time. There are many cases where a lady was known to have provided a great session years ago but provides lackluster sessions now. Some providers do get burned out. If a provider doesn't have recent positive reviews, our first instinct is not to meet her. There are so many awesome providers in the DFW area that guys don't even want to bother with providers who have no reviews or negative reviews.
Especially with provider rates for her time increasing every year, reviews become more & more important. When a guy is spending that many roses, he wants a guaranteed great time and recent reviews helps him decide if he's going to get that. In the end, ladies have the right to implement a no-review policy and gents have the right to not meet ladies who have no recent reviews.