I learned a lot about programming and debugging from Rocky's Boots (https://en.wikipedia.org/wiki/Rocky%27s_Boots) , so at least you have that.

I don't think there has been enough time to say if any "great programmers" (ugh, that's a horrible horrible term) have learned from graphical tools. MIT's Scratch came out (just) 15 years ago, and was quite primitive. Many career developers really start programming at around age 10, so even if they started on scratch, they would be just 25 now. Only beginning their journey to becoming "great". There just hasn't been enough time to say if this is an effective introductory tool or not.