Originally Posted by MassiveD

Many people have successfully used them, or prefer them. The negatives, since you ask are that they aren't designed for it. A touring bike is basically any bike designed for touring. A mountain bike is designed for mountains. There is an area of overlap when your touring takes you to singletrack mountain paths without much need for load carrying. MTBs are also loved as general purpose bikes, and with the right tires or wheels they do a pretty good job of it. For the most part the all purpose thing is the drive-train. We take triples for granted but they came to the consumer market through the MTB.

So in a general way they work, but there is very little overlap, just try designing one. At one point I measured up my 80s MTB, and my touring bike. What surprised me was they had basically the same wheel base. But no two tubes were even similar. Basically the MTB was short in height, in chainstays, and in top tubes, but had a slack steerer. The Touring bike was sorta the reverse. Pretty much opposite.

A lot of touring can be done driving down the road at average speed made good of 10mph. That doesn't take a rocket ship, most any bike has been used for it. My big problem is that my MTB simply isn't comfortable for the kind of hours I spend touring. I think I could get one that would be, but it is supposed to be a nimble climber and downhiller, with a tight turning radius. So there is probably a size missing there. Sorta like trying to tour on a BMX...