Maybe because we are a Free Software community, so we’d like to use Free/Open source tools?
Askbot works quite well and we hosted it on our infrastructure and initially tried to contribute to the development process as we do in the Free software community. However, the reality was that it was not sustainable with the resources at the disposal of the community—it’d be great if some of you could join in and help out here, of course. So, we moved to Askbot being hosted by Askbot. Here, it worked a lot better, and when Discourse came about, we moved because we felt it fitted our needs better.
Most users like Discourse—it’s a great platform. I do not know why you’ve, in your very first post, labelled it as a “poor tool”.