Get off my lawn, punk! 
This is the first verification of system requirements to build, not run, Plone. It should go in the docs.
Both install methods refer to the hardware requirements to run, not build, Plone. I'd accept a PR with text that clarified the difference. Of course, if one person builds a container locally, then pushes that to a repo for others to consume, then the build step is avoided and lacks the extra RAM requirement for consumers.