[mSparks]

i have a project dating back around maybe ten or 15 years that could read the text format (xml iirc) of dia drawings and execute them.

the main problems included being actually very hard to understand visually, very ugly, and subject to all sorts of edge case errors when running. basically easier to write code then compile uml from that for anyone crazy enough to want it.

the crux of the problems is verbosity. Once systems start to get to a reasonable level of complexity the uml diagrams can cover the walls of a large room.

vs 1 page of a4 for pseudocode.