The question http://stackoverflow.com/questions/7730308/list-of-ruby-vms was closed as not constructive.
The OP had done their homework and listed the ones he'd found (15).
The question didn't ask for people to say which VM was better than any other, just which VMs exist, so it wasn't subjective or argumentative. Subjective and argumentative was given as a problem with "List of X" in Should we have a "List of X" close reason?
Is a "List of X" that doesn't mention anything subjective still inappropriate?