There is a limit to this "ideas are worthless" theory. We don't talk about it enough. Instead we either treat all ideas as precious or all as worthless. The truth is much more nuanced than that.
I think people who are just getting started need to know and understand where to draw the line -- and more importantly that other people are already drawing the line in their public communications.
Yeah, the startup process is heavily weighted towards execution, but if you have a stellar idea - and let me just say when I say "idea" I really mean "model" - then sure its got worth. If you know of a stone that nobody's overturned, and hell there's plenty of them you should sure as shit sit on it until you've got a flag ready that you can put in it.
But that only counts if its unique, if your going to build a "OMFG we have a startup that lets you post a 200 CHARACTER status about how what your eating makes you feel" then perhaps the idea might be "worthless" - because thats clearly a business that will make or break in its execution.
So yeah, I agree.
They could have build a vary different company using similar incites with a completely diffident idea and been just as successful, but realizing the cost of really large scale SMS messaging was not prohibitive was brilliant.