Having done big and small consulting work, I think part of the issue is that waterfall still has quite a large buy-in. Smaller shops tend to go more agile, but

Having done big and small consulting work, I think part of the issue is that waterfall still has quite a large buy-in. Smaller shops tend to go more agile, but when you have a team of analysts chomping at the bit to document your processes and say "yes, we can do this" (regardless of if they actually can) that builds confidence. And that confidence is what moves the project forward, until the customer sees dates slipping, at which point it's too late.