>That's extremely bad for community, and I don't know what to do about it
If I were to start a site for online discussion, I would probably not even try to foster a sense of community in the participants.
Although is quite unhealthy for most people not to belong to a community, the human need for belonging is not so pressing that the average person cannot afford to participate a few hours a week on a site that has no hope of ever providing belongingness.
One advantage of having a T/V distinction in a language is that one can set the tone of a site by the address used, informal for "chummy aligned community" (belonging over contributing) and formal for "respectful diverse community" (contributing over belonging). Fortunately english has a formal "you" which we could use to demonstrate that this site is a community of inquiry among diverse opinions, not a community of like-minded folk. Unfortunately english no longer has the informal "thou"[1] so that signal is worth exactly zero bits.
Also, in the old days, T/V was asymmetric. If A V'd B, B T'd A.
These days we use symmetric address, so either A and B T each other or they V each other. (if A are a business advertising, the choice of V or T implicitly segments their market. Some businesses wimp out and advertise in english to avoid making any decision.)
As a German speaker, I can assure you that T/V doesn't necessarily say something about the level of politeness or respect in a discussion. I have witnessed newspaper comment sections or Facebook threads where people would V each other but still say very rude things.
If I were to start a site for online discussion, I would probably not even try to foster a sense of community in the participants.
Although is quite unhealthy for most people not to belong to a community, the human need for belonging is not so pressing that the average person cannot afford to participate a few hours a week on a site that has no hope of ever providing belongingness.