Many people seem to think imperfections in communication tools (e.g., email mailing lists, web forums) are the reason communication is difficult and why consensus isn't reached.

The tools may (and probably do) have an impact, but make no mistake: communication is always difficult. See also Wiio's Laws (https://en.wikipedia.org/wiki/Wiio%27s_laws).

In order to have a constructive discussion, humans will need to put in a lot of effort into it. It's not about tools.