All the games are made for consoles and consoles have a shared pool of ram between cpu and gpu...even if this isn't directly the issue it's still the issue.
Rebar improves the data transfer between ram and vram I guess more cache does the same.
Think about it, you really think all the CPU benchmarks ALL fit completely into the normal cache? Because otherwise we would have huge increases in any CPU benchmark that doesn't fit into normal cache as well.
Most CPU benchmarks are prolonged work where the end result is accumulated a over some relatively long period of time. There is so much its design to do per clock cycle, and the entirety of that work is much larger than the cache. A cinebench run for example isn't done until the whole thing is complete over many seconds. It scales with threads and each thread is working on something different from its cores local L2 cache. It takes so long for each tile to complete that the next bit of data is long queued up and just waiting. No matter how much L3 you have. Which is why it also doesn't scale much with memory bandwidth or latency.
For a game however the CPUs entire principal data set (draw call) is literally a single frames worth of information that it's trying to get to the GPU as fast as possible. The CPU is compiling the details to tell the GPU how to draw a frame, and the GPU's ability to draw each successive frame faster is limited by the CPU's ability to tell it to. Which is in milliseconds. At that speed the prior frame can be out of the way faster than system RAM can put the next batch of data in L3. More L3 allows repeating data to remain more present, while also accommodating more unique data.
Rebar is a memory addressing function over PCIe, which is not incredibly different from when we switched from 32bit for 64bit. That's about improving asset loading which is separate work from the Draw calls. The Draw calls do have to act on the data in the frame buffer so it helps to be able to move larger chunks at a time.
The thing about consoles is that they target a fixed frame rate. Which if its 60FPS is equal to ~16.7ms per frame. Not all games are design for console, but if your port of choice has an unlocked frame rate then the CPU has to turn in its work at much faster rate to keep the much stronger GPU fed to maintain a much higher desired minimum.