Probably a combination of lack of everyday demand and the complexity of the task.

Time is notoriously difficult for many reasons which have been discussed at length [1].

The trend now is that the number of programmers doubles every 5 years [2]. This rapidly expanding group of potential users and creators means features just on the fringe today might become available at any time.

1. https://infiniteundo.com/post/25326999628/falsehoods-program...

2. https://blog.cleancoder.com/uncle-bob/2014/06/20/MyLawn.html