You are making a mistake a lot of people make when talking about genAI helping others do work. I get that to you it is very easy to do, but there are other groups of people that are not able to do it. What you are saying is like a hobbyist carpenter saying that making a bedside table would take him one weekend to do, so he doesn't think it is okay for tables to be made via assembly line instead of hiring a carpenter to do it.
We’re taking about diagrams, all it takes is an experimentation and an iota of thought.
And yet coming up with insightful diagrams, even or especially if they are particularly simple, can be a point of fame (c.f. Feynman diagrams). Diagrams often need to "lie" in some sense, so it can actually be quite difficult to find ways to convey the point you want without misleading in some other important way. e.g. I had a geometry professor that would label the x-axis R^n and the y-axis R^m for a bunch of different pictures, which on its face makes no sense, but it conveyed what it needed to.
People tried to prove the parallel postulate redundant for thousands of years because they lacked the right picture to show why it's necessary.
I think you're missing my point, which is pretty narrow here. "Democratization" is fairly grand term implying that the general public now have access to something freeing they didn't before (it generally invokes some idea of liberation, as the term often is used to note a transition from an authoritarian to a democratic government). I don't think there has ever been a particularly high barrier to making good diagrams, in my experience it's an easy to learn skill both in time and money, so it feels like it's cheapening the term "democratization". Maybe I'm being a bit sensitive though because of how the world is right now with people sometimes literally fighting for democracy. Normally I am pretty lax with semantics but I've had some people really rub me the wrong way when overhyping AI.