Streaming Content and Hard Drive Files

One feature i would like see developed is the ability to play streaming content, e.g. (Qobuz andTidal) and your files on a hard drive, SSD or whatever in one playlist or as a random play from streaming content you have marked as favourites, again along files saved to drives.

Is that a possibility or is there a particular reason it’s not been done because of software quality difference between the two?

cheers

Dennis