The UDP protocol unlike TCP does not have congestion control. This means that if both protocols share the write the TCP will always back off and let UDP use as

The UDP protocol unlike TCP does not have congestion control. This means that if both protocols share the write the TCP will always back off and let UDP use as much bandwidth as it wants. Because router speed is not unlimited effectively UDP will reduce TCP's performance. Also if UDP traffic would grow, there is the danger of congestion collapse, which means that one day the Internet would simply became so slow it would be unusable. This already happened in second half of 80s and was solved by adding congestion control and avoidance to TCP. Why not add it to UDP? You might say. There were attempts, but are unsuccessful due to connection less nature of UDP. This move is totally understandable and provably only thing we can effectively do today. I also don't think net neutrality can be applied here, since there is no discrimination of specific communication between two parties. All UDP traffic is limited it doesn't matter who is using it.