Windows alone uses like 2GB, open some tabs and you are already out of ram. I think 8 is the new minimum.
I have 30 tabs open in Chrome, real tabs, on youtube, PDFs, and code/API docs, and I just cycled through them all to make sure they are loaded, and Chrome is at 600MB.
The phase "open some tabs and you are already out of ram" is a bit of an exaggeration.
That is the opposite of what I see on a daily basis managing several 100+ SMB Windows based computer networks. I'm curious what your summary is to back up 4GB being absolutely fine.