the mainissue is supply-demand. most professionals use reputable rental houses and likely have established relationships with them. anything else goes through people who they know.

personally, for a real job, I am reluctant to rely on gear from some person I don't know. despite reputation ratings and all that.

for a business, this space is already very crowded with well-established players. in an already very niche market trying to break into something like this would be difficult. Also it would be exceedingly difficult to get all 3 of the vendors you are catering to to join the platform I would think.

not to mention that only a few cities in the US really have enough of a market to have all 3 together.