How did most artist back in the 2000s and before sing so good?

I mean Mariah Carey especially in her Christmas album WOW!!! Her voice is outstanding! Whitney Houston, Luther Vandross, and whoever…. Amazing!!
Jessica Simpson, Boyz To Men! I wish I would have lived in the 90s or before to experience it. I’m jealous of Mariah Carey’s voice. Her voice back then was amazing! I grew up in the 2000s so I guess it’s good.

How did most artist back in the 2000s and before sing so good?
Post Opinion