I've often found that diagrams as code is fine for simple things, but once the complexities start adding up, it becomes as much work maintaining the diagrams as it is to main the actual codebase. I honestly think there is little difference in effort required to maintain a diagram in something like draw.io over PlanetUML or ilograph. Time is just spent in different places
Automatically laying out diagrams in a away that makes contextual sense is one of those problems that seems easy, but is actually really hard. If it was easy, everyone would have used dot files and graphviz to generate their diagrams since the 90s
Disclosure: I'm the CTO at hava.io, where we automate cloud environment diagrams, so I'm biased towards automation
Automatically laying out diagrams in a away that makes contextual sense is one of those problems that seems easy, but is actually really hard. If it was easy, everyone would have used dot files and graphviz to generate their diagrams since the 90s
Disclosure: I'm the CTO at hava.io, where we automate cloud environment diagrams, so I'm biased towards automation