Not sure what you mean by "attempting to do shit your thief couldn't do".
Basically, there's generally 3 types of thieves: sneaky types, silver-tongued types, and musclehead thug types. A sneaky types would definitely NOT attempt things like talking it out with people or brute-force their way in, etc etc.
Also, I don't know how someone would know that a particular quest line is the "most open out there in the game" if they just happened to luck into the a build that passed all the required checks for every quest.
I didn't say that in argument of a virgin playthrough. Only that because I've experience most of paths there are in the Thief questline I can say it. It's something to consider when you say how people reloaded a lot during their virgin thief playthrough because there are many possible paths. However, instead of taking the most obvious path according to their invested stats and skill points I'd say people tried to pursue a path THEY *want*. Which, may or may not results in total or partial failure, which may or may not results in them reloading.
The only two ways to really know that is to either save and reload with skills points in the bag multiple times so you can try different combinations or doing the same thing but taking way more time to do it by starting over multiple times and trying different combinations. And if you did spend so much time trying out different skill distributions, you'd have to had seen many failures and would know exactly what I'm talking about.
And this isn't the fault of the system. But I'm also not faulting people who wants to see and try different combinations. I'm also 'guilty' of this myself, as I admitted before how I also reload when curiosity gets the better of me. So why is it a 'problem' for an AoD's virgin Thief Guild questline, again?
Edit: I suppose you could also know how flexible the quests are if you had a list of all the checks but even then the point stands that if you had that in front of you, you'd be able to see how easy it is to paint oneself into a corner with a character that had succeeded through multiple quests prior.
Wouldn't you say this is a matter of not paying attention to the options you're choosing? Of course, there's also a possibility where you're just so hellbent on doing the 'right thing' instead of going with 'what's done is done'.
And I'm serious about this: more often that not it's because players keep demanding for the narrative to go the way THEY *want* it, instead of relying on their stats and skills investment to execute it. There's probably a scenario or two out there where even though you've tried your best with your choice in chardev, the narrative just won't count for it. I doubt there's many of such scenario, though. I remembered even VD and co pointing out how it's actually players expecting things the way they want it to go instead of properly invest in the right stats and skills.
Not saying you're lying about getting through the first time without hoarding skill points but I know for a fact that you can very easily have the right character concept and put points into the right skills but not in the right combination and if you don't have skill points saved or know where you can pick up some skill points, you're screwed. And I know this because after getting stuck and having to start over well into the questline, I did experiment with the checks.
But is that really the fault of the system? Wouldn't it be right for you to, instead of keep banging your head against that wall which happened to be there, go back and do stuff somewhere else? I'll admit it can come of as kind of tricky when it comes to this game's noncombat gameplay elements, but from what I remembered there are a lot of opportunities to increase your civic skills other than quest-related stuff, like a merchant's goods or a sleeping people to steal from or a chest to detect, disarm traps and lockpick, or trainers which can raise your skills or give free SPs. And if the problem lies in which numbers you got to have the skills in a given city, isn't that rather simple? 3-4, 5 for high difficulty content in Teron, 5-7 in Maadoran, 8-10 in Ganezzar or beyond? And if we go by this logic, then why do we insists on hoarding SPs up until we encounter a skill check? And then you might ask, what skills? Well, what kind of character you want to play as? There's a matter of 'useless' skill, like Etiquette, but this ain't the problem with the system and more with the problem of content design, like how in Fallout 1&2 First Aid and Doctor were largely useless to tag at chargen.