This is impossible without working at TikTok, and being intimately aware of their algorithm, neither of which I am. But I would lend credence to this saying because it seems to be so obvious to the users of the platform. They learn quite a lot about how it works through observation alone.
Agreed, without working there, you're just speculating.
Given the possiblity for abuse, and the value from abusing it, I assume the worst: they are abusing it and probably worse than either of us can imagine.