(UPDATE) Man, where to start? What Walt did with film making, technology, copyright, marketing and celebrityship (if that can be a word) laid the foundation for the world presently we have. I would compare him to Thomas Edison, or even Steve Jobs. I think the key thing here is power. Walt had a vision, and an incredible sense of direction. By a combination of charisma, determination, and what I believe were just plain lucky breaks, Walt saw ways to go beyond what even Windsor McCay was doing. And he wasn't afraid to push the envelope.
But success has its price. There are many stories of artists who created great works, but quite a few were impossible to live with. Walt was going to get what he wanted, and that was that.
The established studios that were successful at the time seemed to keep Disney on the run. Mintz studios? Gone. Fleischer? People still remember Popeye and Betty Boop, but those characters belong to King Features. Warner Bros. has Bugs Bunny, but with no "Walt" or Chuck Jones at Time/Warner to support him, he's fallen by the wayside.
Micky Mouse is known around the world, and is here to stay.
I will try to have another update asap.