Based on my experience, it's very hard for people to accept something new in the first place, for example, when WP was introduced. And this is still happening now. Once a group of people accept a new concept, building on top of it to improve the system is a little easier.
OK. Thinking about it, there might have been a market there all along, but how come no one served it before? I mean Jason is crazy brilliant (talk to him, it's an experience!), but surely others could have come up with the same idea - right? I guess we'll never know, but my guess is that not too many people went out and searched for a thing like WPEngine before WPEngine
There are 75 million (!) WordPress sites in the world. It would be amazing if any software platform with 75 million users didn't have a large number of consultants available to help people with it.