That’s one part, and it’s big. I believe the other part is that triangle strips are more efficient because they can share vertices better than quad strips.

Of course, but that's not generally true. Why use two triangles for e.g. a rectangular floor? The walls and the ceiling are also rectangular after all. Probably mixing and matching different polygons isn't very efficient either.

About collision: I don't know how it is computed, but if it's by ray casting, that is now also used for lighting effects and sometimes reflections. Which would be another reason to stick to triangles.

The Playstation, at least, supports quads as a draw primitive. It does decompose these quads to tris for rasterization[1].

The Nintendo DS actually supports both tris and quads as rasterization primitives, which has some interesting consequences for shading[2].

[1] https://psx-spx.consoledev.net/graphicsprocessingunitgpu/#gp...

[2] https://melonds.kuribo64.net/comments.php?id=13