I noticed that in almost all open source projects, the main avenue of communication is the mailing list, or multiple mailing lists for big projects.
Every time I want to ask a question, I have to sign up, and it's usually not a very friendly or intelligent system. Memorable messages include: "Do not use a sensitive password because it will sometimes be mailed to you in cleartext" and "This is a reminder, sent out once a month, about your python.org mailing list memberships."
Then I have to mail my question in and wait for other people to answer, while in the meantime my inbox gets flooded with long threads about the project which are of no interest to me. After people have answered my question I still have to remain registered for some time, just in case someone will still have something insightful to say. All the while still getting unwanted messages. After that I have to interact again with the mailing list software to unsubscribe.
Why? Am I missing something here?
Web forums are fine for many people, but they drive me nuts. Too much clicking and too many pageloads, at least for the forums I have seen. This breaks my communication "flow" and leaves me feeling unwilling to spend any more time at the forum. It _is_ true that it is easier to drop in and ask a quick help question in a forum, as you point out, but that doesn't outweigh the fact I usually never want to visit the forum again. More fundamentally, my async store/forward communication happens in my email client, I don't like having to switch to other programs.
Now, don't get me wrong. Mailing list discussions are far from perfect. In particular it's easy for the entire discussion to be hijacked by a few hot topics. (Not necessarily trolls, although that works too.) This inflates volume and drives away people who would otherwise make great contributions. I've seen this repeatedly.
Really what I'd like is something that is to mailman what git was to version control -- a way for me to opt in to different "versions" of a mailing list potentially managed by different people but sharing the same core message flows. Something that would let me avoid needing to keep my own set of killfiles updated for each list all the time.
The Cypherpunks Distributed Remailer sort of tried this, but their focus wasn't on different filters. They never had that many nodes anyway. The other thing I've seen is people self-tagging posts with [<keyword>] in the title, but that is brittle and still requires me to create new filters on the fly.