It's also a poor congestion control practice to begin with. The main categories of UDP traffic are DNS, VoIP and VPNs. DNS is extremely latency sensitive -- the entirety of what happens next is waiting for the response -- so dropping DNS packets is a great way to make everything suck more than necessary. VoIP often uses some error correction and can tolerate some level of packet loss, but it's still a realtime protocol and purposely degrading it is likewise foolish.
And VPNs are carrying arbitrary traffic. You don't even know what it is. Assigning this anything less than "normal" priority is ridiculous.
In general middleboxes should stop trying to be smart. They will fail, will make things worse, and should embrace being as dumb and simple as possible. Don't try to identify traffic, just forward every packet you can and drop them at random when the pipe is full. The endpoints will figure it out.
And VPNs are carrying arbitrary traffic. You don't even know what it is. Assigning this anything less than "normal" priority is ridiculous.
In general middleboxes should stop trying to be smart. They will fail, will make things worse, and should embrace being as dumb and simple as possible. Don't try to identify traffic, just forward every packet you can and drop them at random when the pipe is full. The endpoints will figure it out.