I imagine that many maintainers who don't necessarily feel as dogmatic about free software hold the belief that "if you wish to contact me, you will use the tool I say." I've certainly "maintained" projects that are free software that I had no real desire of spending much time on, so if someone had a question it better come the way that I want, otherwise I can just ignore it. It's not a very kind or classy position, but I think a lot of people feel this way.