Turns out, there is a lot of advanced routers, firewalls, IDSes, etc.. which like to inspect and filter the traffic, and they often drop unknown protocols. As

Turns out, there is a lot of advanced routers, firewalls, IDSes, etc.. which like to inspect and filter the traffic, and they often drop unknown protocols. As a result, new IP-based protocols are likely to have the connectivity problems. So all the development moved to be UDP based.