I've had the misfortune to work with a Java developer who insisted he didn't know JavaScript and therefore wouldn't ever touch JavaScript code even if it would have saved everyone a ton of time. Yet at the same time the Java code would often generate HTML or even JS code directly.
There are companies with stupid silos like this, but for the reasons I laid out I doubt they actually benefit from the "toy-language templates" approach -- even in the aforementioned company the non-developer designers would implement the entire layout as a mockup in HTML and then toss it over to a frontend dev who would cut it up and add the actual template logic (because although the template language was "easy" non-programmers couldn't be "trusted" to get the logic right).
There are companies with stupid silos like this, but for the reasons I laid out I doubt they actually benefit from the "toy-language templates" approach -- even in the aforementioned company the non-developer designers would implement the entire layout as a mockup in HTML and then toss it over to a frontend dev who would cut it up and add the actual template logic (because although the template language was "easy" non-programmers couldn't be "trusted" to get the logic right).