In contrast, as you say, there are huge amounts of armchair ideas that are not worth very much even if they are correct. For example "software will eat everything" is something I believe is mostly right. It is also a business idea with direct implications for action. Despite this, it is only valuable to set the general direction (let's do software), but not any specific cases. It does not mean that every case of transforming a traditional business into a software one is going to be a grand success, or even profitable. In fact, these types of ideas have a tendency to cause one to forget the exceptions from the rule, and thereby being actively harmful.
Maybe it's because many of the ideas in the "ideas are nothing" category are twitbook/fourit/squaresnap/flickchat/... clones, rather than ideas like "let's build a product for market X using tech Y to reduce problem Z".
(Edit: In some ways we do have such a framework. For example, I am sure that venture capitalists have a lot of paradigms for doing just that. But this meme of "ideas do not matter" still persists and is oft repeated by venture capitalists themselves.)