The trouble with dropping groups

The permissions-stripping group membership is very reliable in every Unix to date.

That doesn't mean it's not a little icky, or that we can't move forward with better ways today, but unless the better way also reliably supports both NFS (various protocol versions) and other operating systems (not everything is pure Linux) then demanding that everyone switch to doing things in a way which doesn't expose the Linux change as a security flaw is only going to create acrimony for the high-handedness.