This can currently be done using renderlayers, but doing it in one render can be faster.
These passes are useful because they make it easy to tweak the lighting in scenes after rendering has finished.
There still are some ToDos left - the biggest limitation is the maximum of 8 light groups, but this is a tradeoff between number of passes and kernel memory usage.
Another question is how to handle denoising for these layers.
Depends on D3538 since it also has multiple named passes of the same type.