i completely dismiss scratch as an actual visual programming environment. i honestly don't think of it as visual programming at all because it simply takes a text-based language and replaces the syntax with blocks rather than spaces, semi-colons, brackets, etc. i personally feel it is misguided. dynamicland is more of a visual programming environment than scratch is.
so here, you are taking what amounts to a toy and something directly marketed towards children as your shining example of a visual programming language.
in my opinion, labview is the most complex, general-purpose visual programming environment, and people have clearly written rather large, complex applications with it. why isn't it adopted more? a lot of reasons, one of the biggest ones being cost. the other the association with a particular domain, but i consider it a general-purpose language. even if one gets passed that, there is still a huge bias that text is still THE way to program and interact with computers.