Counterpoint: it's actually wack to cut you off from any area at any point. No reason for it is given and no reason would be given in your proposed scenario. I'm all for choice and consequence, but you have to tell me why I have to make a choice first. The fast travel system is based on magic runes, not actually traveling places, so there's no reason you couldn't hop back and forth from waypoint to waypoint. Like there are plenty of ways in which the game already "makes you lose story elements" based on choices you make. You lose several companions if you play Act 1 a certain way, and you lose a different companion if you play it the other way. So I'm not opposed to that kind of thing, but you have to tell me why, and it needs to make sense. Someone brought up the way it was done in The Witcher 2, but I actually didn't like that. There's not a real reason for Roche to demand that you do his thing right now, and that demand is ultimately the only thing forcing you into a decision. Otherwise, you could either persuade Roche and Iorveth to play nice, or use Axii and force them to play nice. And the game ends up hedging on the whole thing and having you go to the same place anyway, just on different sides and with less agency in the overarching story if you take the Roche path.
