The L in DSL is "Language", so it's a programming language that is domain, or niche, specific. These are code.
Diagramming is a domain, and within diagramming are any number of diagram type domains, leading to concise code for particular niches.
Compare 25+ of these niches here: https://kroki.io/
I’d say my premise isn’t that “DSLs are bad”, but more along the lines of if a DSL isn’t what you’re looking for, I may have something for you. Particularly if you need your application to generate a view of a graph _during runtime_ so that it is your real-time source of truth.
I find that DSLs and “as code” solutions for several products have their own niche. Take for example Terraform vs Pulumi.