Why no Dependent Matrix Type?

Hello, I don't really know how to really introduce this topic. Background: I want to implement compile time safe matrix multiplication. For that i want to have a struct with const generics for the number of columns and rows. Then i want a function which takes two const generics and does the matrix multiplication. The result would be a matrix with the different sizes. So far so good i was able to implement this. One idea is sketched in this old post. Now the caveat is that this works only ...