Why std_data_json is not default in phobos

[JN]

On Thursday, 22 February 2018 at 09:45:25 UTC, Jonathan M Davis 
wrote:
> Well, while that's definitely a problem, it really has nothing 
> to do with why it's not in Phobos (no attempt to get it into 
> Phobos has occurred since well before 2.077.1 was released), 
> and if it _were_ in Phobos, then the regression would have been 
> caught by the autotester, and the code that caused it would 
> never have been merged - which is one advantage to having 
> something be in Phobos rather than on code.dlang.org.
>
> - Jonathan M Davis

I believe it's a common practice in other languages to do 
something like testing the compiler against top 20 (or more) most 
popular packages, while I doubt this package would make it to top 
20 (do we even have such metrics from dub?), do you know if 
something like this is being done for D too?