Despite the continued theories and speculation, I'm pretty certain that outside of supplying false information, the mysterious deactivation has to do with only one thing -- errors. They can be large or very small, or even just due to the reviewer themselves making a mistake or signaling it incorrectly, but once you hit a certain number, it's gonzo.
The problem -- well, one of the problems -- is that they don't always tell you the reason. I know someone who was deactivated and he did find out what he had supposedly done. It was just a few very small errors over quite a few years, and to do with the report itself, not the actual shop -- things that were blatantly obvious and easily fixable. Quite honestly, in this particular situation, they were things that other companies would have excused, counted off for in the shop grade, or given feedback that would have cautioned against future errors. I don't shop for them often because I don't like the way they communicate, very much like you're in a vacuum.
My guess is that Market Force has lost a lot of good shoppers for very silly reasons.