RAM Doubler or something like that was an actual working thing back in the days, that worked by (IIRC) transparently zipping/unzipped data on its way to/from memory.
On the other hand, SoftRam 95 took the driver kit paging driver and claimed to compress data, but actually didn't. All you got was a small buffer in memory where pages would be paged to before they actually got paged to disk.
But yes, I agree.