There are varying level of sponsorships and typically if someone claims to be sponsored but runs in "sportsman" classes then I agree with your concerns, however the majority of my sponsorships explicitly forbid me to run in sportsman, that's written into the contract.
There's also a big difference between a "sponsorship" and a "factory driver" who actually gets their gear for 100% free of charge where factory drivers are the cream of the crop, majority of factory drivers also earn contingencies which is another method to measure the level of a skill a driver presents for the team.
As far as rebranded electronics go, I would raise caution with AGFrc branded servos which are lower quality with no warranty or support. There are some US based brands which special order premium upgrades to their servos and rebrand them under different names where I know NitroPro offers significantly upgraded servos with one of the best warranties on the market, more info here: