I kinda agree, and I mostly switched to mermaid because of availability. Plantuml is much more annoying to setup, and doesn't render natively on GitHub (last I checked, anyway), so if I writing anything more collaborative, mermaid requires a lot less explanation or help with setup.

And for me, one mediocre tool that works everywhere for everything beats a better tool that requires me to context switch too often, so I mostly retired Plantuml. Not happy about, but alas.