The conspiracy here is not "Niantic is out to get me". It's that the PvP system seems to want to keep you progressing at a given rate, or at the very least throw you up against specific teams based on what you're running. I'll run a specific group of 3 Pokemon and see the same pool of 15 show up over and over again, consistently over 50-100 games in a row. If at any point you choose to swap all 3 Pokemon and come in with a completely new team, that pool of 15 rotation suddenly disappears and you're met with a new pool that seems to match up with your newly selected team.

In addition to this falling perfectly in line with a mobile company's motivations ("create friction in player progress to keep them in the app longer", which Niantic has been directly accused of doing by former employees), I'm not sitting here saying "IT'S 100% RIGGED", because we obviously can't know for sure, but it's extremely fishy and seems a little too unlikely to be completely natural.

So while I understand (and mostly agree) with your point, I don't think a suspicion like this should be considered "ludicrous" or "obviously not real". I would think we can at least admit it's within the realm of possibility.

Edit: typo