This change is sort of changing the behaviour of forum posts to more resemble twitter. People are more likely doing short and simple posts and less likely to post longer and more in depth posts since short simple posts are less likely to have mistakes that you won't be able to correct due to the banning of editing posts.
If I wanted to do political discussions in a twitter format, I would use twitter. One of the advantages of a forum format is that it is supposed to allow for more in depth discussion, but getting rid of post editing eliminates one of the main advantages of a forum format.
I don't really get how 1 person (cybercoma I think) going on 1 post deletion spree in the 10+ years this forum has been around justifies eliminating one of the most essential features of any forum, post editing. The fix is worse than the problem.