Generics don't solve immutability.
The blog posts topic was not "immutable data structures", rather the need for boilerplate code in Go because of the lack of generics. The particular example was one of immutable data structures, however that was an example rather than the topic. The author themselves notes that "generics would solve all of the issues above".
> No, Generics make it possible to create a generic immutable data structure
I am sure i can read.
James' comment you quote was responding to your comment, which he parsed generically as "Generics don't solve T", with a comment of the form, "Generics make it possible to implement a generic T."
I'm confident you can read, but I'm not so sure about your reading comprehension and critical thinking.