Why are some types from std not in the core of the language?

[zjh]

On Sunday, 12 June 2022 at 14:34:23 UTC, zjh wrote:

> What should we do if even `experts` can not 'correctly and 
> completely' realize new features?

The reason why there are few contributors is that the code can 
not realize `class level encapsulation`!
Without `encapsulation`, the code is a `mess`.

A bunch of `thousands of` lines of `code files`, how to 
contribute?
Why not split it into `dozens of` small files into hundreds lines 
files?