Originally Posted by MichaelW
Back in the 1980s, a guy built a touring MTB, capable of hauling campoing loads off-road, and that weighed in at 22lbs.
I think most MTBs are built for the worst-case scenario, ie over-weight newbie riders with little skill, riding extreme jumps. If you are lighter, can ride well and avoid Kamikaze descents and Big Air, you can ride much lighter bikes.
Don't forget the need for loads of cash. With enough money just about anything can be done.
My Hardrock weighs in at about 27lbs now.