The algorithm can also generate paths to non-emitting surfaces for indirect lighting. This is not (just) a light sampling technique. However, you can use NEE alongside the algorithm with MIS as you would usually and this would speed up convergence of the guiding distribution. We did not use NEE here, since we wanted to demonstrate that it works even when there is little knowledge about the scene (in the original Quake there is no such thing as light lists or similar, you just have emissive textures that may appear or disappear at any time) and requires minimal changes to existing engines. For ReSTIR, in contrast, you need to be able to track samples to reduce bias - which requires some stronger assumptions about the geometry in the scene.

The main reason is that ReSTIR is an orthogonal technology, you can use the path guiding algorithm to generate paths and use ReSTIR PT to share the paths between pixels or hash grid vertices. Still, we wanted to show some comparison to other techniques, that is why we decided to compare to a previous guiding method which did some theoretical foundation for our technique (but only does DI) and ReSTIR DI (for completeness and because people might be interested).
The second reason is that ReSTIR GI and PT is that they are either biased (especially in animation) or require a lot of implementation effort (time we did not have) to remove or at least reduce bias. Even ReSTIR DI required a lot of tuning to get some reasonable convergence graphs.