I'd also like to emphasize that no Rust template engine – that I'm aware of – does context-aware escaping. At least Maud has it on the roadmap.
But if someone's publishing a HTML templating system, and they don't have enough knowledge about HTML to understand the need for contextual escaping, I would have grave concerns about the Dunning-Kruger effect & the quality of any software that engineer writes.
I think a better way of terming this would be that you have concern the the author might not have enough domain expertise, which is very different than being incompetent.
This gives me pause that Maud isn't right for a production system at this time, but is that so surprising for a 0.11 library?
I guess what I was more getting at was the thought process that goes "I'm going to develop and release a library in X domain", when ones knowledge of said domain is low. And then launching said library before one has really gained a lot of knowledge of that domain.