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.
I've seen plenty of Rails apps that could have written better initially. But I haven't really seen any where it was impossible to refactor and improve them as a developer learns more.
The difference I'd say between Clojure is you learn those from the bottom up, whereas with Rails you learn from the top down. Either way, you are going to have to learn them!
I think the biases of people who were experienced big system developers before they moved to Rails, are very different from those who started with it, potentially not understanding web app development very well, and then produced something challenging to maintain
Having used both Ruby/Rails and Clojure, I think Clojure swings too far in the opposite direction, where absolutely everything is foisted on the developer and they must hold the entire codebase in their head at once or drown.
We even see this in luminus, the closest thing Clojure has to a web framework. It's just a leiningen template which spits files out on disk and says "there you go, it's your problem now". Of course there are upsides to this approach, but personally I've come to find developing web servers in Clojure a withering, joyless experience. Elixir and Phoenix show much more promise and seem to strike the right balance between featureful-ness and cleanliness.
I don't get that, and if that's how you feel I'd say you are doing functional programming wrong!
That being said, I do agree about Luminous and I think it's a terrible way for a new web developer to Clojure to get started. Instead build your way up for what your app needs pulling in the libs as you need them and understanding how they fit and work together. Chances are you don't need that many at all.
I'm gonna try Phoenix for my next project, even though I really like Django and I have never been too much into rails or ruby. My other option would be Django + socket.io, and I think that would be the more mature stack, but as much as I like javascript and python I think that would lead to more complexity and thus make the project harder to maintain. I may be stabbing myself in the foot, but let's hope not :D