I am posting this video without very much comment.  It speaks for itself.  If you listen to current singers versus older singers you will find that the older singers have much freer voices than those of today.  You will also notice that modern singers often use amplification.  This was never the case with older singers.  I will put the youtube link below so that you can read the commentary there, if you like.

https://youtu.be/xxLqkp4pTA0