6MT drain plug (oil pan side) rounded off

I changed my 6MT and rear diff gear oil today. I stupidly used a 12-point socket and rounded off the 14mm drain plug (oil pan side) . Tried to undo my mistake. I used more PB blaster, propane torch, 6-point socket... it was not coming off.

 

Is this is a common problem? I read a thread on IWSTI where someone described this bolt as "made of butter." Is the engine oil drain plug prone to rounding?

If this happens to anyone else, I was able to drain most of the oil anyway. I lowered the front tires to the ground and lifted the back end up as high as I could (I'm guessing 21" because that's the max travel of my jack stands). A lot more oil came out through the T70 drain plug hole.

 

Capacity is 4.3 qt, and I was able to add 4 qt of Extra-S fluid, which took it to about 3/4 the way from the Low line to the Full line. I checked the dip stick last night, after driving about 200 miles this week, and it's right at the Full line when warm.

I did pretty much the same exact thing. Started with a 12 pt and rounded it off, then tried vice grips that made it worse. On to bolt extractors that just shredded the bolt head to nothing. I couldn't believe how soft the metal was. I took it to a shop and had them get the plug out, and I just assume they drilled it and used an easy-out.