I've played Rolemaster and as detailed as it is, it's not trying to mirror reality.
It's trying to come pretty close!
Realism is a spectrum, and not just one spectrum.
I take it that by "is a spectrum" you mean "is a matter of degree".
In which case, yes, realism is a matter of degree. When it comes to D&D, basically, the more significant some thing is as the object of attention at the table, the less likely it is to be realistic. I mean, that's a generalisation, probably an over-generalisation, but not a
gross over-generalisation.
In this respect D&D resembles other pulp-y or "B" adventure fiction.
(Just one example: how often do shoes - mundane shoes, that keep one's feet a bit clean and a bit uninjured - come up in D&D play? Rarely, in my experience.)
That it's not realistic for the group to keep being confronted by monsters, dramatic events and opportunities, has nothing to do with whether or not some other aspect of the game should be more realistic in someone's opinion.
But it does have something to do with assertions that departures from realism are at odds with the spirit of the game.
Not to mention that claims about "realism" are often made about
mechanics - which doesn't even make sense! - rather than about the fiction, which is the thing that actually exhibits a lesser or greater degree of realism.
(By analogy, some novels tell more realistic stories than others; but there are not more and less realistic ways of writing novels. Just as with a RPG,
realism is a property of the fiction, not a property of the method of authorship.)