Is the Front End Controlling the Complexity of the Web Application?

In the early days, what you could call forms over data application, where it was bilt, here's just a bunch of data entry screens. And when you do that, where does all the complexity reside? Where does all the tacit knowledge live while it lives in the end users? So then you have these highly trained end users that when they leave the company, everybody gets terrified because there went everything and all the knowledge. It seems to me that's the state of a lot of web applications, where the front end is controlling the system rather than the other way around.