A certain custom template engine made by some bored developer who had too much free time and thought he could create something better than other widely used template engines. He somehow convinced the lead dev of the company at that time to use his wonderful creation and it is still there after many years.

Spoilers: it is not better than the template engines he copied the features from, and it somehow fucks up certain parts of the css and javascript which makes it a real pain in the ass to work with.