Thanks for speaking up about this - I think a lot of developers who have been using Java and other OO languages for a long time can and do need time to swap to the functional methodology. It's *not* because the developer isn't smart enough or is incapable, it's simply a very different way of thinking and it takes time to rewire the brain.
A couple of small things which might help:
* For me it helped that I'd done SmallTalk in the past and saw OO as passing messages/events between immutable objects. This mimics one common aspect of pure FP in that you never change state, e.g. 2 + 4 = 6 - When you add 2 to 4, you're not changing the value of either 2 or 4, you're applying a function (of sorts) and creating a new value 6.
It's not the *only* aspect to functional programming, but I found it helped me overcome one aspect.
I'm sure others more experienced at teaching FP will weigh in :-)