Like Firefox, in Google Chrome you can reopen a closed tab (right click tab at top or Ctrl+Shift+T) and your post will be there right up to the last character you just typed. It remembers all closed tabs in a session and still works even if you completely close Chrome (or if it crashes).
I've found that, with both Firefox and Chrome, this only works if the last instance you closed was the one with the post.
Right now, on my desktop machine, I have 5 browser instances open, and probably 25-30 tabs. And I'm not even sitting there. In the particular instances I was mentioning above, I was closing the browsers to do patching in one case (so the machine rebooted) and was in a huge rush in another case (and just had to quit everything).
In most cases, you're right... If I realize immediately what I've done. My issue is that I'll walk off to do something else, and might not come back to it for a few hours (or want to "resume" the post on a different machine and platform). Reality isn't so clean, in other words...
In any case, if that plugin isn't flaky (and it seems to be simple and common), it'd be nice, and much simpler and more flexible than all of the suggested workarounds (which I am aware of, but as Inflatable mentioned, that takes forethought).