Well I think it's a good idea to prevent web pages from just opening up a socket to some server, speaking whatever protocol they like. It could be easily abused to spam, etc.
There is, however, https://www.w3.org/TR/tcp-udp-sockets/ - see section 10 for an example.
Considering the move proposed in this thread to move even SMTP to HTTP, how would preventing connecting to SMTP prevent spam when one can still POST to SMTP-over-HTTP?
Re:DNS-over-HTTPS
by paulddraper on Friday September 30, 2016 @11:13AM
(#12612932)
"We need to restrict this to prevent abuse."
-- time passes --
"We need to change everything in order to accomplish a task under these restrictons."
Which is ridiculous, as it literally brings zero advantage to restrict that.