I have implemented the algorithm you’re talking about, in shipping systems, probably 15 years ago. Maybe I forgot some detail, but if you’re trying to make yourself hard to discuss with, you’re doing pretty well…
What I’m saying is that modern rendering won’t interact well with those older techniques. Unreal focuses on the modern rendering. Hence, they don’t want older techniques. From their point of view, that makes sense, because that’s what their goals are. If you want other goals, use OGRE or OpenSceneGraph or whatever. Plenty of life still left if those systems if those are your goals.
Except now your triangles need to be ordered in painter’s algorithm, because they all alias in Z.