There is a big difference between an SP that doesn't have any reviews on the board and one who doesn't allow reviews. Also, contrary to some beliefs not having reviews on the board does not stop discussion about SPs in back channels. It does, however, stop those who don't have back channel contacts from getting info, which means newbies generally. Most of the most personal, intimate info or info that would not be tolerated on the public forums appears in back channels. So, it's important to make the distinction between those who have no reviews and those who don't allow reviews. With the former it's a crapshoot and TOFTT. With the latter the people who've been around can still get info and make informed decisions whether public reviews are allowed or not. There's a built in handicap for people who are new to the scene.
Personally, when I was still seeing the generally available SPs I would decline to see those that didn't allow reviews. Not seeing them wasn't an aspersion on their personalities or abilities but rather with such a large selection of people to choose from and with so much info available why would I choose to see someone who refuses to allow info about them to be made public? It may or may not mean anything, but it may also be a flag, and I'd probably rather take a chance on someone who has no available info rather than someone who refuses it, just because it seems like the odds of someone having a reason to hide their info is less with an unknown quantity than with a known hider of said info. Again it could turn out either way in either case, but it amounts to playing the odds somewhat. With prices being what they are these days it makes sense to choose based on available info and reviews rather than choosing an unknown quantity. You could make the case that it's like online shopping and that the trend line over a larger quantity of available positive info/reviews is something to look for when filtering potential dates. Yes, I understand that there are fundamental differences and a human aspect to SPs completely absent from buying on Amazon but some of the same principles apply regardless. You just need to apply the right filters.
Not my circus, not my monkeys, since I don't have that problem, and everyone can determine what their own individual risk factor is, but minimizing risk (whether monetary or experience risk) would seem to me to be a good thing. Informed choices are always better IMHO.