I actually believe the opposite. Jumping into and doing Clojure web development is extremely simple at the core. The issue with frameworks like Rails (and I'm not against Rails as I have used it on multiple successful projects and still think it's great) is that you get so much for free and don't have to understand how all the pieces fit and work together (at least initially). Soon enough you have to have more knowledge of that and that's were the complexity comes in.