It isn't locked to a single route, that statement is blatantly false. I've unlocked 3 endings myself, there may be more, but I can't be sure.
My review at least, clearly refers to the fact that your choices have little to no effect in what the character ends up experiencing, regardless of the ending (that is, getting blackmailed and fucked either way, no matter what you chose at the start). This doesn't mean I said that the game is broken in any way.
I have a dislike for how the plotline progresses and takes away player agency, but that doesn't mean the game isn't working. There are varied paths. My main irritation comes from the fact that there is no way to avoid being a slut as the story progresses (disregarding the ending,) not whatever you're talking about here.
It is also painfully clear that the other low star review refers to the same, so I'm unsure what you are talking about.