>>850It's really not any more or less efficient than playing records, sushi roll. Tapes have a specific audio compression which gives them a certain 'feel' that can add to the listening experience, smoothing out otherwise raw and jagged demo recordings or adding a sort of comfyness, if that makes sense.
Lots of demos and even albums are only released on cassette, depending on the genre you're into and for compulsive collectors like me its another fun thing to collect (especially since a lot of these demo tapes are rare and/or have never been digitized).