The Admin CP still doesn't use templates, even in 5.x. That is to say, Admin CP pages don't have templates associated with them.
The template system for front end pages has existed since at least 3.0.x. I'm not sure before that.
According to this post even VB 2.0.0 had templates:
https://www.vbulletin.com/forum/foru...2-0-0-released
Is it possible your Administrator account just doesn't have access to see templates?