I just watched the video that Taeha Types uploaded today with rmendis, a moderator at the MechMarket Discord. I think the video has interesting points that are informative for new people in the hobby as well folks that have been here for a while. I won't regurgitate every point (the video is an hour long), but I'll just highlight a couple of points that resonated with me:
rmendis brought up that minimum order quantities (MOQs) used to serve as a sort of "evolutionary mechanism" (his term) that could help weed out sets that were not popular enough to survive group buy. As more people (and more money) entered the hobby, some vendors or organizers simply bypassed ("bastardized", rmendis said) this weeding mechanism by just throwing money at the MOQ, and worrying about demand later. This practice delays the failure: if there isn't at least minimum demand a product now at a certain price, it's likely that there won't be minimum demand for product at a year or two later at a higher price.
But more importantly, rmendis brings up the idea of a more centralized and voluntary code of conduct or set of standards for vendors. I think something like that would be a great step forward for the hobby and a huge net positive for everyone. A standard of conduct, perhaps denoted by some sort of branding (something akin to B Corporation branding), could help customers distinguish between vendors that are willing to publicly commit to things like transparency, consistent communication, & responsible business practices, and those that are not interested in the scruples of such commitments.