RAM Doubler was a third-party application in the days when a top-of-the-line Mac had 128MB of RAM, with a 40Mhz processor. The level 2 cache was 256 bytes.

That's not in the same universe as hardware compression on a 6-core, 64-bit ARM processor with cores that can run at 4GHz.

That is why it is an old trick

Sure, but there’s a difference between a hack and an intentional architectural decision.