Give us LFR (but without changing difficulty), boss specific loot locks instead of raid ID and a DF style group loot rolling system as an alternative option to pugging and let the GDKP people do what they will. Maybe their way will be more popular, maybe accessible group loot pugs will be more popular. Let the players decide by having more easily accessible alternative options. I think that’s better than trying to “ban” GDKPs. Just give those of us who don’t want to do GDKPs better pugging options and let people do what they prefer. Guild groups are unaffected either way (though they’d also benefit from boss-specific locking potentially instead of raidID).
If it’s not already possible, also allow any size raid up to the raids max queue together so you could also make a pre-made or partial pre-made if you want to be a bit pickier about classes/gear in your pug and then queue together instead of going in and doing master loot/gdkp.
inb4 LFR is satan comments