I am on MBP mid 2014 15". It has 16GB of DDR3 memory. With just Slack, IntelliJ(not even doing anything), and Chromium browser I'm sitting at ~10GB. There is no way I would ever buy a laptop on which I intend to work with, with less than 32GB.
For comparison, I have exactly the same MBP mid 2014 15" with 16GB.
As I type I have Slack, IntelliJ (with large Scala project), VSCode, Spotify and Chrome with plenty tabs open, and sitting comfortably at ~7 GB.