Yes, those are the exact situations in which the post gets lost. And yes, ctrl-A ctrl-C is your best and easiest defense against this. What Bitt is saying is, for those who forgot to do ctrl-A ctrl-C and lost their post, this is the fix procedure. In an emergency, after your text has suddenly disappeared, you can pop up this thread in another browser window and get your precious text back.

The fix procedure only works if you've already installed those plugins he mentioned when you make the mistake, though, so having the plugins already installed is a good idea.