Between being clear on what the game world norms are and giving a PC second chances to rethink courses of action that may not be ideal, the DM is still letting the player make the PC's decisions and act on them
Again, to be clear, I'm wanting to respond here not to the particular course of action that Elf Witch's roommate took - I wasn't there, I don't know any of the people involved, nor what the dynamics of the group are, nor how they like to play RPGs - I'm just trying to present my own reflections on GMing practice which have been triggered by the OP.
To me, a Wisdom check suggests that the GM is trying to resolve something in the gameworld - a niggling urge, for example, at the back of the PC's mind, or the hairs standing up on the back of the PC's neck. I prefer a game where that sort of thing is reserved for Perception and Insight/Sense Motive, but
not for issue of moral/aesthetic evaluation, in respect of which as GM I leave matters up to my players and as a player I want the GM to leave matters up to me.
If I'm playing and the GM thinks I'm doing something that is silly either in the sense that it has obvious consequences ingame that I may have forgotten about (eg I mention my PC bringing out a ham sandwhich because I forgot, last session, that we were told the duke is vegetarian) then I would rather the GM just say something - a stat check seems unnecessary (given that the forgetfulness is clearly on the part of the player, not the PC). Or, if the GM can see some player conflict brewing among the players and wants to issue a caution, just do it - again, calling for a stat check is not how I would generally go about it. Again, the problem here is not the PC's lack of insight or awareness, but the
player being about to do something silly. So why punt it back into the gameworld and the PC's stats?
More generally, the approaches that I described as somewhat foreign to me seem to be premised on an approach to the game where the norms/values of the gameworld are determined by the GM, the players' role is to accept and explore them, and conflicts of value among the players and/or GM are sublimated into ingame issues via alignment rules, Wisdom checks etc. Obviously I'm aware that such approaches to the game occur - when I say they're foreign to me I don't mean that I've never heard of them. (For example, something like this approach seems to have been dominant in letters to Dragon magazine at least around the mid- to late-80s, and also seemed to be fairly standard in a lot of 2nd ed play.)
When I say that it's foreign to m, I mean that it's very different from the way I prefer to go about RPGing. I've never seen any evidence that the "sublimation of conflict via alignment rules" approach to handling disagreements at the table is an effective one. And as a GM, I want my players to decide what is valuable in the gameworld, and what is not (so, for example, and as has happened in games I've run, the PCs, whether indvidually or as a group, can decide that prudence requires compromise with Vecna, or that their duty is to oppose heaven and work with a god exiled by heaven, or that the slaughter of unconscious hobgoblin captives is a legitimate response to depradations inflicted).
