Also a factor is that there are very useful libraries that either can only be used in nightly, or are more ergonomic to use in nightly. Usually because they rel

Also a factor is that there are very useful libraries that either can only be used in nightly, or are more ergonomic to use in nightly. Usually because they rely on compiler internals or unstable language features. This is mentioned as one of the points under "Challenges for Rust".