There was a brief period where everyone and their dog implemented mustache[0] as a template system, but it died quickly because cross-language templating is not that useful in the end, you seldom need to switch host language but keep the templates.

0: https://en.wikipedia.org/wiki/Mustache_(template_system)

I think the craze was about "purity" of mustache as presentation-only template engine. Apparently you need some level of logic to be useful.