Adding List Order By Metascore option (and hide the ones if metascore is not available or show them with a title at the bottom of the list)

I am pretty sure this has been asked before but why don't we have this feature? I mean sorting the list according to their Metascore with both ASCENDING and DESCENDING options.

I know not all the movies have a Metascore available but majority of them do. I have a list, for example, that I am planning to watch and out of 54 movies on the list, 49 of them have a Metascore. And I want to watch them starting from lowest to highest Metascore. And for the movies that doesn't have a Metascore, they can be temporarily hidden when sorted by Metascore OR they can be displayed at the bottom of the list with a title something like "Metascore not available for:" 

Why haven't this feature implemented yet? Is there a specific reason for this?