As somebody whose instinct always goes there, and has pushed for that kind of extensibility and generality in review threads, I should note that I’ve already received thoughtful responses about why these things do belong in the compiler.
That’s not to say the “bolt-in” criticism is always wrong. In hindsight, differentiable programming probably never should have made it into the language. Distributed actors…it remains to be seen. I’m skeptical, but eager to be proven wrong!
Just saying that sometimes the “bolt-on” criticism is misplaced. People complained about property wrappers and function builders being too SwiftUI-specific, for example, but they’ve turned out to be wonderful and widely useful. That criticism was misplaced in that instance.
For a person like me who carries around a bit of that Ruby-ish instinct of “don’t make the language do it, make the language make it possible to do it,” sometimes the type safety, optimization, or system integration advantages of stuffing something into the language itself are surprisingly compelling once I actually understand the problem properly.