I'm skeptical of this actually being the case in any real-world scenarios. There have been a number of tests of running games from a RAM disk vs an SSD, with precious little difference in load times.
It depends on the data generally, but algorithms like lz4 can decompress faster than most storage mediums can keep up. Including nvme drives. Compare 1.8GiB/s reads of raw data, versus compressed almost 3 or more. This is on a skylake i7 and 2 nvmex4 drives. More cpu use but honestly, it would be stalled waiting on i/o otherwise.
The key is the data sent to the cpu and decompressed, makes up for the stall from hitting memory or i/o. Comparing ram vs ssd is the wrong comparison to make, with both you're hitting stalls due to memory. You want to compare reads of uncompressed versus compressed with the note that (and i'm just making numbers up with this analogy as i'm about to sleep), 900KiB of compressed data in, 2MiB of data out. 1.1MiB bonus and yes I'm assuming huge compression but for times your cpu is idle it makes perfect sense.
And yes, lz4 compression on things like movies still helps. I shaved off over 200GiB on my home nas with zfs.
I'm skeptical of this actually being the case in any real-world scenarios. There have been a number of tests of running games from a RAM disk vs an SSD, with precious little difference in load times.