I think Erlang/OTP probably has a higher learning curve than other frameworks, but I guess is a lot down to history. As another poster said Erlang solved this problem 20 years ago, where as more modern languages are typically based on the C syntax, so they share a lot in common.
Back to your point though, I think once you understand the language it is actually a lot simpler to understand what is going on. Modules are usually very self contained, and you don't get the layers upon layers of indirection you see in other frameworks (I'm looking at you Rails). I think the functional style of programming as well helps to keep things simple, it doesn't make sense to have a 20 line function in Erlang.
Back to your point though, I think once you understand the language it is actually a lot simpler to understand what is going on. Modules are usually very self contained, and you don't get the layers upon layers of indirection you see in other frameworks (I'm looking at you Rails). I think the functional style of programming as well helps to keep things simple, it doesn't make sense to have a 20 line function in Erlang.