So in the early days many people had their home pages on FTP servers rather than HTTP servers. Of course, technologies may get replaced by better solutions over time. The Web is in constant evolution. At any time there are old and young technologies working together. It has to be like that.
Technologies improve at different speeds.
Trying to release even three or four new specifications in sync is already stretching our capacities. And throwing away software that works, although imperfectly, and teaching everybody something new would be a huge waste of resources. There is, unfortunately, a tendency in every standards organization, W3C not excluded, to replace everything that was created by others with things developed in-house. But even if that is true, maybe the improvement still isn't worth spending a working group's resources on. And especially, don't design a technology to work only with things that haven't proven themselves yet, no matter how promising they sound.