I think you've taken it backwards. The comment you were replying to is listing features that lead to robustness (many of which appear in strongly-typed functional languages in the ML family), not essential aspects of functional programming languages.
Indeed. I was listing the specific items the article (titled 'Why is F# code so robust and reliable? ') lists. Functional programming languages only came up to reject someone suggesting Rust as a language that can be included as robust/reliable in the context of the article's reasons for F# being robust/reliable
