I run a virtual machine (to which I allocate 8GB), Qt Creator, chrome, safari, slack, iTunes, Skype, Sourcetree (all of the apps that are deemed to be memory hogs) and some more support tools, and I still have memory to spare. I have the impression that macOS has got really efficient with memory management. On windows, I never keep so many applications open (mostly due to non-existing window management)
Inefficient programs with shiny GUIs.
OSX + GPU + Chrome + Hipchat alone consume over half of the available memory on my machine right now. And that's just the software which supports my development, no editors, compilers or VMs.
Start to throw in modern editors, VMs (software which behaves very poorly when swapped out), compilers that trade memory space to reduce CPU usage, or a JavaScript heavy website, and you're one errant command away from your machine becoming unusable as it starts swapping like mad.