Well, I think there's a bit of mandatory-ness that comes with adding it to Ruby itself. Sounds like the standard library is going to ship with rbi files defined, for instance. Plus, tools for generating rbi files. On some level, it's an endorsement to do things this way, right? And that's before it (potentially) becomes a community practice to do so.
If it's not, why not leave these solutions in gems?
Btw, I don't think static typing alone is Ruby becoming all things to all people. In recent history, it's also aliasing `Enumerable#filter` to `Enumerable#select`, numbered block arguments, a shorthand special notation for `Object#method` -- it feels like a trend of "hey these other languages do this, we should too". I'm not convinced that's always the case.
If it's not, why not leave these solutions in gems?
Btw, I don't think static typing alone is Ruby becoming all things to all people. In recent history, it's also aliasing `Enumerable#filter` to `Enumerable#select`, numbered block arguments, a shorthand special notation for `Object#method` -- it feels like a trend of "hey these other languages do this, we should too". I'm not convinced that's always the case.