That would certainly annoy the heck out of me.  Couldn't you just write a big article off-line & then copy & paste when done? 

The most convenient way to solve that, imo, is a clipboard-history program like ClipDiary. Saving progress is then as easy as ctrl+a to select-all, and ctrl+c to copy (thereby storing it in the history, from which you can easily recover it in cases like the above).

Android has versions too. (the one I use on there is Clip Stack)

yes... when WC went through a period of crashing frequently.... quickly learnt to CtrlA CtrlC as I went along... and if it was a particularly longun'... pop it into Notepad...cause often it would crash after Post Reply and you'd just get Boom & Egads!!!... and a rewrite never seemed to get done as well as the original...

i've seen some forums that autosave periodically

Especially on white wine nights?  Or beer binge nights?  I any event, I know the feeling.

I recall typing out this really great joke for one of the joke threads a few years ago, and it was quite a longish one, too, so when it disappeared after I clicked 'Post Reply' I screamed something rather similar that went something like this:

"AAARRGGHHHH!!!!!! FUCKIT, FUCKIT, FUCKIT, FUCKIT.... FUCK IT.... FUCK IIIIITTTT!!!!!!

Nowadays I save posts to the clipboard if there's site issues... just in case.  I must say, though, things have been so much better recently