> Is a wontfix with lots of comments more expensive, than a wontfix with comments blocked?

Yes, it is more expensive. When 100 developers are CC'd on a bug that is generating regular "but did you consider this argument?" comments, it's a lot of overhead.

You could argue that everyone CC'd should remove themselves from the CC list when this happens, but by that time we'd already have taken the hit.

These bugs are not fun for anybody, dev or unhappy user alike.