2. Should that even be a thing? Do you think game designers allowing that is a mark for or against them?
I mean, in general any game design where it actually becomes impossible, by designer intention (as opposed to eg game breaking bug which is also not good but a different topic), to win,
without actually losing in short order, as a regular, intentional occurrence, is bad.
That's a lot of qualifiers, but it kinda needs them.
Some game designs, such as, for example, a lot of competitive designs, may have you reach a point where realistically you've already lost without the game declaring you defeated per se. As an example, a lot of real time strategy games can have your infrastructure wrecked to the point of being unable to recover without it meeting the conditions for defeat per se. This is basically fine, as long as the match isn't likely to be
significantly drawn out after it's reached its effective conclusion. As another example, a lot of RPGs can have you in a position where it's not longer possible to win the battle, but the game still needs to go through a few turns killing you off.
A big part of what these scenarios have going for them, though, is that they are the emergent consequence of the situation and not something that can be
easily addressed. For example, if your RTS would declare a player dead when they lost all construction buildings, without needing to lose their units or other buildings, you could see cases where each players army starts destroying the others base, and because one was slightly quicker at taking out the buildings that keep their foe in play, even though they had the weaker army they won. This can be acceptable, of course, but the point is that this kind of hole in the design space isn't actually easily closed.
(By a similar token, most fighting games have it
strictly always possible for a player to make a come from behind win, but realistically if you are sufficiently far behind in health it probably won't happen, due to the need to go from being consistently outplayed by your opponent to consistently outplaying them.)
The kind of situation you are explicitly describing, meanwhile, is often something that could be easily closed up without harm to the design, or even is
entirely intentional and required
manual effort on the developer's part to create. A lot of older point and click adventure games require you to do specific things in early scenes or else you'll later on, without explanation or warning, be unable to actually keep going, even though the game will equally refuse to declare you as having lost. There will be, by intentional design, no backup option, no solution if you do make the wrong choice, etc.
Sometimes it'll be more innocuous, like dropping a quest item in a place you can't return to, where this ideally shouldn't have been possible but it's not clear that the developer did anything worse than overlook that risk, but the kind of design where you can do things like kill off plot critical NPCs, the game provides no alternate way to reach a culmination of the plot without them, and then it also doesn't do anything to kill you off or whatever, where you just wind up in what amounts to a softlock situation,
by design? That's straight up bad design. Regardless of whether it's because of 'realism' or 'player choice' or whatever, there should never be a situation where the game is still going and you can't actually reach an end state at all.
