Designers alone can't push through a change for the sake of change as their work relies entirely on user research. Even if they do have the research needed to prove a change is required, they also have to get developers on board.

So I don't know where this conspiracy theory comes from, but it's entirely unfounded unless you're talking about a designer like Jony Ive with the power to go through multiple obstacles with ease, in which case the change isn't happening to prove he's needed but because he has a different vision.