I wouldn’t add memory to a system unless and until the memory pressure runs into the yellow or worse. More parts means more chance of failure, less chance that good compression and swap happen.
In fact, we’re seeing the same thing on 2017 iMac and newer in production. We get Apple NVMe SSD and they are so fast, the stock 8 GB of RAM is faster in almost all cases than bumping up to 16 or 32 GB of RAM.
There are some very limited cases where you need more memory, but generally, you want to not run web browsers and other buggy / leaky code and adding more RAM just gives them more room to make a bigger mess before you clean them up.
Even Photoshop and Illustrator - crank their undo buffers down to an accurate size for the needs instead of giving them 8 GB of RAM for scratch so they keep around undo from 4 hours ago.
These days, the performance bottleneck is almost in order:
- The human
- Just bad software (things that take CPU in the background, constantly wait for network tracking and can’t work offline or communicate only when there’s something to do)
- Network slow
- Server slow (SMB / local servers)
- Storage slow (especially non SSD / non NVMe storage)
- Maybe now you might need a CPU bump or some more RAM - but maybe not, so measure before and after to change setup.