Yeah, I would agree that there are different ways the GM can force things, and some are worse than others.
And I agree that prepping things ahead of time does not have to result in the GM forcing things. Just that it’s predisposed to do so.
Certainly it is more likely than with a no-prep GMing style, right?
I think it depends on how no-prep the GM is, and how willing the GM is to admit the story that emerges from play belongs to the PCs, not the GM or anything the GM owns. I can imagine a hypothetical GM running a hypothetical no-prep game where the story ended up being more about the NPCs or some other aspect of the world than about the PCs, where nothing the PCs did changed the direction of the story; I can even imagine it happening unintentionally, without malice or bad faith. I can also imagine a hypothetical GM having at least where the PCs are prepped to the door hinges and running so the story belonged to the PCs; this seems far more likely to be an intentional decision. I'll admit that both of those might be fringe cases--the former probably more than the latter, I think.
That said, there is definitely a temptation to use what you have prepped no matter what the PCs do, which kinda by definition doesn't exist if you have nothing prepped.