I have often struggled with the comment section on SE sites. I think that oftentimes it comes down to web anonymity and the fact that people say things online that they most likely wouldn't say in person.
Very rarely (read: practically never):
Is any question (of any quality) asked out of spite or mal-intent
Is any mistake bad enough to deserve being name called, or labeled in a derogatory fashion
Do such comments communicate anything constructive that could not otherwise be conveyed in more thoughtful and considerate words.
I do think that often, we will say things on Music.SE that we might be sensitive enough not to say in person.
While in day to day interactions, a person may very will think to themselves:
I find this sort of question both pointless and rather sad.
It would much more likely be expressed as something closer to:
I don't really think that this kind of question is very productive.
Or maybe even:
Maybe readers would come to that conclusion on their own anyway, and it avoids even the potential of creating offense.
Now, while I would posit that sometimes voicing this sort of concern can be constructive and helpful, as with all social interactions, it is important to do cost-benefit analysis before you type. Like mommy always told ya', "Think before you speak." (Also, look both ways before crossing.)
Questions that display a clear misunderstanding of the topic that they're about aren't because the asker is there to waste your time or be rude - even if the problem is as fundamental as misunderstanding the Stack Exchange paradigm. They're simply learners.
Grace and understanding ought to permeate all of our comments, especially from the higher reputation members of our community, who, and I can speak confidently as a lower-rep user, are looked up to and respected. For a newer musician who really, really just wants to learn, the way they are treated and encouraged (or discouraged) by other more developed musicians can make or break their journey through music.
People and relationships are really important -- in fact, they're more important than the craft. Remembering that, especially online, and even when we're on after a hard day at work, is I think the best way to conform to the Be Nice policy (which is really one of the most important.)
For that reason, I agree that the sort of comment you described would probably be best modified or removed. Very much in same the vein of thinking as the recent blog post on the Stack Overflow blog about being nicer to new users, we simply must promote a welcoming and nurturing environment to new users, and reinforce our relationships with older ones to build a stronger community, by being careful and thoughtful with the words we choose when expressing our thoughts to each other.
After all, people are way harder than music theory.
