Because in the past you had to use servlets directly, or JSPs that you had to do a lot of work manually to separate business logic from the presentation layer.

Because in the past you had to use servlets directly, or JSPs that you had to do a lot of work manually to separate business logic from the presentation layer. Source: I worked at a Web startup circa 2000 where we did exactly that. I think people sometimes forget how far we've come.