If you read once more what did I say you'll find out that I DID NOT say there are no pure FP languages. I've spent some time with one (Concurrent Clean) and I DID like it!
I am not using it now though, noone around here would be able to cooperate with me :-(
The reason why did I like Clean was not because it restricted me (no side-effects), but because of the restriction it was able to offer something (laziness). Of course the generality of the type system and ability to compose functions at will was appreciated as well.