So I think V tentatively accepted Thais' first quest despite not really wanting to do it, then pretty much ignored her quests etc for most of the game until today. This didn't create many issues, but it did create one or two.
- It of course never becomes obvious how to remove the rockfall if you never get past the spying phase. V assumed this was what the Tool Of Destruction was for then was a bit frustrated by lack of option there (for most of the time I've been trying not to backseat-game for them).
- Some things can end up feeling very out of order: you can still inform Thais about the Old Pagossian plague even well after you went and cured it and had that confrontation with her, so it felt odd to still be able to inform her, like, today, when it's probably ten plus hours of gameplay after Old Pagos got cured. Also that's parly why Thais got bypassed for so long, because V was like "Well Thais clearly hates me now and probably won't talk to me anyway" and then they discovered about Steep House and then no longer wanted to talk to Thais.
- V wanted to help White Marshes right from the start, and I'm not even sure that Howler's Dell rallying people against White Marshes gets raised as an option until later in Thais' line so you don't know that that's even a possibility to work towards (not that a "good" warden would trust Thais to do it once they know about Steep House). So if you bypass that then it's no longer obvious that Thais is an easier option, and you end up staring at Thyrsus going PLEASE TRUST ME to little avail.
- I think (I may be wrong) that you probably need to get at least as far as clearing the rockfall to have helped Howler's enough to get the druids' support, I'm not sure what the locking points are there? And V hadn't even reported the plague until today because they hadn't realised they needed to and were being confused & frustrated at how to progress the Howler's + Steep House plot, because you're just wandering by going "I now know you're evil but I don't have any idea how to get support against you."
So I think the issue is that if you take some other plots too far, it's no longer at all obvious that the gating feature for a major possible solution is "you need to go back and talk to Thais" because it feels like those things have gone past the point where you'd want to do that? Or because you didn't talk to her to start with those options never really open, so you're left with a reduced palette of more difficult options where it's much less obvious how to achieve them, which can make a player hit a bit of a late-game wall. I'm not at all sure how one would fix any of that or indeed if it's a problem that needs fixing rather than just a problem of some people bringing behaviour codes into the game that it wasn't intended to encompass - maybe in one or two places an extra pointer or two in the journal might help?