I disable QUIC in my network because I'm doing QoS at my router and utilize TCP flow control to slow things do to where I want them to be. QUIC makes the incorrect assumption that the network never wants to slowdown or to even allow for a configurable speed. Don't be too clever.
Why use flow control? Why not just a traffic shaper like altq/dummynet/whatever? Do you really only care about TCP traffic and not torrents, games, VoIP etc.?