By and large, RAM speed doesn’t do very much to improve average FPS. The actual benefits, even with Intel CPUs, are found to be in FPS minimums and lows, which increase with higher RAM speeds. Any game will experience occasional FPS drops, sometimes minor, sometimes severe. With a faster RAM speed, these drops can be better alleviated to the point where they are less noticeable or not noticeable at all.
Since Ryzen is more susceptible to slower RAM, these points matter even more for AMD users.