I am a very bad choice to use to “prove” your theory. I think your theory is that CS regulars post there, get known by the Support Forum Agents, then get made MVPs with “special privileges”. Those privileges as far as I can tell are the publicly known email address to the TS/CS MVP lead, and the TS/CS Discord.
I was not asked to be in the MVP program for my posting on CS - so I am one of many who was not a CS regular when selected. I was asked if I wanted green after a year of being the one doing most of the basic TS helping on Diablo 3 TS forum. One of the Tech Support Blues nominated me I guess. That was 10 years ago. Discord did not even exist, there is no compensation.
I don’t know what you think goes on in the Discord, but it is not the hand rubbing and plotting some might dream up. It is boring, addresses policy changes, addresses emerging issues with “did you guys see this yet?”. It is also a place MVPs chit chat with each other about mundane things, although that is rare. There are not many of us left.
If your “concern” is that MVPs are selected from people who the staff are familiar with, yes. Of course they do select from people who have an active posting history that the Support Forum Agent is familiar with. Your post history is what they use to judge you, of course they use people who have an active post history that they know.
And then, the “reward” is green text with people targeting you, taking out anger directed at Blizzard on you, making assumptions about all manner of things, etc. Oh, and a Discord with some of the Support Forum Agents. Not all, by any means, but a couple.
None of this is secret. None of this is some sort of conspiracy, plot, or nefarious doing.
Fun fact, most of the TS/CS MVPs are not CS regulars and don’t post there often, if at all.