Erlang, like all other systems, really works in some scenarios, but not in all of them. I enjoyed that they really broke that down instead of presenting Erlang as the next panacea for all ills.
I'm an Erlang fanboy with no misgivings. I think the things that Erlang does better than say, Python, it does so much better as to make Python disappear. And the cases where Erlang is clearly the right choice are a bit bigger than some people give it credit for.
Of course, I write Erlang professionally, so I would say that. But I can tell your right now that it's giving my company a competitive advantage.
A screw driver is a pretty multi-functional tool: you can undo screws with it, you can push the cork in a bottle of wine, I guess you could shank someone with it. However, that doesn't mean most of those uses are optimized.
I'd much rather read an article that says a screw driver is an awesome way of inserting or removing screws (much better than saw a hammer) than read one saying it's the right solution for every problem. Personally I open wine with a corkscrew, and no, I've never shanked anyone.
Nice that the article gives a good run-down of advantages and disadvantages.