Real-world use: https://github.com/pixelspark/warp/blob/dcf57462bd400df6d067...
(the typealias thing is a bit weird here, I agree - it also doesn't crash without it. Nevertheless this compiled fine on 3.0 and should show a nice error, not require me to leave out every other file from the build to find out where it goes wrong, then bisect that file to find out which line causes it)
Until recently the focus was on finishing the design of the language itself and not fixing bugs or improving compile time. Now that the language is source stable the focus is shifting to the latter two tasks.
Also source stability means we can build up a larger body of code for testing (imagine having to constantly migrate unit tests that exercise corner cases and quirks... not fun).