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.