I guess the bottom line is, would we truly say the things to a person's face that we are typing here? Since we're all strangers, I think we should act as if we're meeting strangers in person, with no background about what might offend them, and handle them all with "kid gloves", so to speak.
I think that comparing online to offline is apples to oranges. Would we say these things to people offline? Often times, probably not. Because offline we're interacting with our friends, our bosses, our kid's teacher -- i.e. all people that we cannot have, large and by far, honest conversations with. That's not a critique, just a reality.
People edit conversations based upon their relationship
to the person they're speaking to in order to maintain peace and achieve goals. If your boss and your six year old child asked the exact same question, even when about a completely benign subject (the first thing that came to mind is stoplights and how they work), you'd give them different answers. In the stoplight example you'd probably assume your boss knows certain facts already or, even if you think they are completely clueless, you still wouldn't want to *imply* you think they're clueless of basic information adults who drive know so you'd act as if they knew these facts. So, your answer would assume they already knew these facts whereas you'd assume your child doesn't know these basic facts adults who drive know and answer in accordance to that -- to give a concrete example, I wouldn't assume a six year old has worked out that a blinking yellow or red light means "slow, watch for cross traffic" but I'd expect anyone who drives knows that and wouldn't include that fact in an answer.
In the case of internet conversations with people you don't know offline, which is by far the case on these boards, you don't have to edit based on whether a bad implication might get you assigned the job no one likes because your boss is upset you treated them like they were clueless. You also can't reasonably assume a lot of things you would be able to with someone you know -- for example, I can't assume the other adults on this board drive or that they live in a country where the above is true. So, you just answer the way you see things and work out any misunderstandings as they come up. It's a very different type of interaction and isn't comparable.
In a reply here you said:
But isn't this like saying that in order to be "real", we sometimes have to disregard someone's feelings?
In short: yes. And, also, of course. I'm not regarding your feelings in my reply right now because I don't know what your feelings are beyond my interpretation of the ones you expressed in your post which I may be misinterpreting without context of other behaviors you display (i.e. I can't even interpret your post in context of what area of what country you live, your gender, race, age, etc. since I don't know those things). I don't know you. I have no reasonable way to figure out whether something I say will upset you beyond the very basic "You're a meany poopy head!" type statements which would, obviously, upset anyone.
Now, you can argue that "You're being too sensitive." is one of those meany head type statements but since I only really remember seeing those pop up here in response to a poster asking "Am I being too sensitive?" I wouldn't categorize them like that. Similarly, I know the driving thread of which you speak and in that thread part of the stated (by the OP) reason the OP thought it was rude to be called like that was because of the annoyance of answering a phone while driving. If the OP is annoyed by answering a phone while driving then, rather than see that as a problem of the person calling them, it's far more reasonable to ask why they answered.
Basically, I see very few statements here which come apropos of nothing. The replies come in context of the questions or the situations described on which the questions are based.