This issue is a meta-issue regarding procedures for the CSSWG itself. This issue will not result in a change to any specification.

I've put some proposed text on https://wiki.csswg.org/spec/css-fonts regarding a test that each new proposed generic font family should have to pass.

For each new generic font family proposed, the proposed generic font family must pass a test to be considered to addition to the spec. This test is necessary, but not sufficient, for its addition.

The purpose of this test is to limit the proliferation of generic font families.

1. There needs to be at least two distinct fonts in the world which can map to the generic font family. In this case, “distinct” requires that they are invented by different unaffiliated people or groups.
2. Because generic font families are only relevant for installed fonts, at least two major distinct operating systems need to ship a font which would be mapped to this generic font family. Again, “distinct” requires that the operating systems are invented/maintained by different unaffiliated groups. These two OSes can ship the same font.

I put this on a wiki page in accordance with #4606 (comment) where we resolve for me to start a wiki, and whatever we decide will be edited into that wiki page.