Not necessarily. You're leaving out 'defeat', which in no way needs to imply death, and the failure to achieve desired goals/objectives.
That's a good point. Many D&D combats seem to focus on killing the monster/NPC or die trying.
So far, the distinction has mostly been between time-critical and time-neutral encounters.
But there are more types of encounters or adventures:
Think of a hostage situation. It will take some time until the kidnappers will actually do something bad to the hostage. So, the clock is ticking, but on the "per encounter scale".
But once you are in the encounter where you meet the kidnappers with the victim, now the time is on the combat scale - It is really bad in such a scenario if this encounter is your typical big-boss" monster encounter, because this will mean that some of the villains will survive long enough to have a reasonable chance of killing the hostage.
For have it work, the hostage guards must be "mooks" - it is now not a question if the characters will kill them at all, but it is a question if they can do it in time before any kidnapper gets to slit the throat of the poor hostage.
This scenario is exciting and difficult without ever entering a long-term resource management, nor requiring a life or death scenario for the characters.
Addendum:
In D&D 3, the lower level / mook encounters serve as attrition. But does that mean that the individual encounter becomes more exciting because you lost some hit points and spells? Or does it just mean that the last encounter becomes more interesting, because you might or might not have enough or the right ones left then?
If that is the case, is the fourth encounter worth the first "lame" three ones?
Or wouldn't it be more fun if I had just some "fool around encounters" where players get to figure out their new cool abilities (warming up a bit), and then run into the meaty encounters that are all thrilling because you have to use your wits and all the (encounter-renewable) resources available to you?
How important is it that the resources that I have at my disposal during any specific encounter is based on my daily resource management (as opposed to the choices I made on character advancement, maybe).