Rock music was born in the 20th century.

Anyone who will study classical music composition will inevitably study about 20th century classical music and the loosening of tonality and classical structures and be influence by that and believe that to be a positive development

As that is the era where I believe classical music jump the shark. This will always produce music that is inferior in my personal ears.

This applies to prog rock where the incorporation of classical music into rock music never works perfectly due to this.

Although saying that, my explanation is the reason why I don’t think there can be great living composers in general rather than focus on composer with a rock music background