It's an odd arrangement with the ROPs versus the L1. The RDNA whitepaper considers the ROPs clients of the L1 and touts how it reduces memory traffic. However, if their output is considered write-through, what savings would making them an L1 client bring?
Given screen-space tiling, a given tile will not be loaded by any other RBE but one (no sharing), and unless the RBE loads a tile and proceeds to not write anything to it, the L1 at best holds ROP data that is read once and must be evicted once it leaves the RBE caches (no reuse).