This is essentially a statement that the system shouldn’t be unnecessarily complex. And sure, but that’s not really relevant to the discussion.

If you have a complex system, whether due to legacy or due to actual necessity, you aren’t going to redesign the system just for the sake of simpler explanation. Indeed if someone couldn’t explain the system in its current state I would have zero confidence they could successfully simplify it.

My point was that the attitude of being able to explain systems by drawing them, leads to over-architecting them. If you stick to prose then you can't as easily delude yourself about the complexity by staring at pretty pictures.

I was not considering the case of documenting already existing systems, just talking about the planning stage. Your point is well taken.