...just an example.
Don't pick such a complex example. Pick the absolute simplest. Try to write Blink with graphical blocks. What would the blocks look like to unambiguously define everything that the Blink sketch does? Don't take any shortcuts. You must explicitly define everything that the "block compiler" needs to know.
I see two possible outcomes:
-
There is just one block called "Blink".
-
The number of blocks roughly equals the number of lines of C++ code. There is a block called "delay" and one called "digital write".
In case #1 you have a system that is totally locked in to what the block-designer could think of. In case #2 you have re-written C++ but with arrows instead of semicolons.
Humans have been programming computers longer than they have been flying airplanes. The pinnacle of that evolution has arrived where we are now.