I would like that in XF2 this kind of things could be avoided.
Now we can quote selecting the text from the original post and add it to the "quote queue", why don't lock the quote text in the reply box so people can't break it?
how about a "tag health check" that warn the user that tags are not well formed (for example there's no closing tag).
I'm the only one that see this problem? I have to better educate my users? maybe!