Although I've never heard of D2 until now, it seems like too much programming for a diagramming language. I've used PlantUML for diagramming since couple years

Although I've never heard of D2 until now, it seems like too much programming for a diagramming language. I've used PlantUML for diagramming since couple years and it seems good enough. You need to learn their DSL but you don't have to manipulate visual entities manually.