We've reached the limits of the flash technology which drives both the SATA and PCIe versions of the storage device
Individual chips have an upper cap on speed, but that's why every SSD on the market accesses numerous devices in parallel. All you need to do to make an SSD go faster is add more NAND devices in parallel and a slightly faster controller to support them.
Flash is not all that fast and it quickly becomes the limiting factor on how fast you can read data out of it.
Maybe if you have no idea what you're talking about.