@gothpanda @colinstu Also, this code was released 32 years ago and made its way into a lot of places. Being permissively licensed (public domain being the most permissively license [or, technically, lack of license] possible) enabled this and is a big part of the reason that the web was a success.
There are a lot of examples of protocols with permissively licensed reference implementations becoming ubiquitous. There are very few examples of GPL’d ones. If you want a protocol to take off, make sure that there’s a permissively licensed reference implementation.