I think that's a mistake in the article, we will follow semver after 1.0.0, and we definitely don't want a 2.0.0 less than two years after 1.0.0. I'm sure crystal will provide the same stability guarantees as go and rust.
Aside from tooling I need a guarantee that my code, if following all of the best practices, should be compilable from now till the foreseeable future.