"lighter voices are more common" - is this true? why?

I think what may be more true, is that lighter voices get more encouragement early on. Is the person who just can't blend in the choir going to make it beyond high school chorus if they're continually berated by their director for being too loud? I think early on there is more emphasis on "pretty" inoffensive singing. These are the people who are rewarded and encouraged in high school and college. If someone showed up to school singing like Mario Del Monaco, I think more academics would be bothered than thrilled. Just my two cents.

-RH