It's not that it's hard, it's just the logistics of running the virtual machines(s) and the applications they contain. You could use a minimal linux distro like

It's not that it's hard, it's just the logistics of running the virtual machines(s) and the applications they contain. You could use a minimal linux distro like Alpine or Tiny Core, but you still need to run applications on top of that if you're testing or developing. Spinning up a basic devstack instance (for example) take a minimum of 6GB and that's before you even deploy any test vms inside that infrastructure. Another example, if you're doing config management development you may need several VMs running which in turn may have (say) large java apps with heavy memory requirements even when fairly unladen. So, I guess the answer is, it depends on what you're doing and what the memory requirements of the thing you're running on VMs is.