I have 8GB here, under Debian. I can easily run docker (with a rails server), firefox (discord, slack, facebook, youtube, online radio + outlook webmail, all at the same time), with many Emacs windows.
I think I could manage to have less RAM (I frequently code on my chromebook with 2GB RAM). My theory is that the ram expands to the amount available https://en.wikipedia.org/wiki/Parkinson%27s_law
IIRC at my last employer an Asana tab + Slack ate ~1.5GB all on their own, and Asana was so slow to load that one hated to close it.
Jira's not as bad as Asana but depending on the set-up it can be pretty close. Then there's Invision, et c which are much lighter than those but still pretty damn heavy, if you're trying to get by on 4GB or less. And/or maybe you've got Outlook and Teams and all that. And that's just the communication & collab tools, not even any of the stuff to produce actual work output. Temporarily having to use a 4GB machine with that kind of workflow is why I'm now permanently on Basic HTML for Gmail—it loads fast enough I can close it, and uses so little memory there's no reason to. I couldn't spare the 300+MB for Inbox or whatever with all that other junk open, and besides, Basic HTML's much faster.
I think I could manage to have less RAM (I frequently code on my chromebook with 2GB RAM). My theory is that the ram expands to the amount available https://en.wikipedia.org/wiki/Parkinson%27s_law