They give an explanation here.
526 karma · joined October 8, 2011
Edit: While `const PI = 3.1415…` is threadsafe, it's not very useful in comparison to runtime-immutability :)
"Non-goals: make channels completely lock-free (this would significantly complicate implementation and make it slower for common cases)"
[1]: https://blog.mozilla.org/javascript/2013/07/18/clawing-our-w...