They do, but eventually even the polite but grumpy comments build up to the point that it looks bad. These comments are public -- that's the whole point -- so the only way to hide them is to delete them. Normally this upsets users even more, so the "trick" is to "improve" the service by dropping the entire forum on the floor and starting over with a new piece of software. Not because it's better in any way, but because it is an implicit DELETE * FROM "BUGS".
Microsoft is on their... what... third forum now? I lost count.
That's a tremendous improvement when compared to the time I interacted with them.