There isn't much need for many applications to know or care what IP protocol they are speaking, they are all just writing bytes to a TCP stream. I think the par

There isn't much need for many applications to know or care what IP protocol they are speaking, they are all just writing bytes to a TCP stream. I think the parent is saying that existing socket abstractions meant that these applications still had to be "upgraded" to support IPv6 whereas it could/should have been handled entirely by the OS with better socket APIs.