While I know that there are a lot of horror stories (and I can tell a few), some of the most productive "programmers" I've ever met used MS Access or Excel.
If you don't consider advanced usage of these applications as a form of programming, then you are illustrating the point: It is not only possible to "dumb down" programming, it is inevitable. So much so that you haven't even noticed it happening.
I'm talking about "general purpose software," which encompasses a huge volume of space. Rare is the person who can competently address the wide variety of problems found in the world of software. Excel and Access, in my view, are perfect examples of paring down the acceptable problem space to something reasonable and making tools for people to solve those specific problems naturally. You can't write a 3d engine in excel, but that's okay, because the tool is not for that.
But this argument breaks down when you try to take it to a general-purpose software kit, which has to handle anything and everything. In this wide, unshielded world of hard problems you have to have the most capable and powerful tools available. Deliberately limiting tools in this environment is like saying, "Our river pilots have lots of experience handling barges, so it'd be counter productive to train them on oceangoing vessels, we'll just build bigger, sturdier barges for ocean travel." Yes, sailing on the open ocean requires more powerful and complex tools, but you appreciate those tools when the ocean gets rough.
You can, a guy has done it. I'm only being pedantic because this is cool if you haven't seen it:
http://www.gamasutra.com/view/feature/3563/microsoft_excel_r...