We have bold, code, and italic buttons, but there's a lot of use for crossing out words.
I guess you have something like this in mind?
d̶o̶e̶s̶n̶'̶t̶ ̶w̶o̶r̶k̶.
This is a great way to catch attention in the post and show what is not working/not good.
Let's see how people will vote, but I think you are totally right. I can imagine a few headlines that would be much better with this feature.
Thanks, Luka, for the idea!