You're just talking about the style of one era. Styles keep changing.
Listen to how male singers sounded in the 1930s. For example, "Ukulele Ike," (Cliff Edwards) was fabulously successful. Listen to how he sings "Paper Moon," 1933.
<a href="https://www.youtube.com/watch?v=cQHOe9JP2tw" style="color: rgb(17, 85, 204); font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">Cliff Edwards ("Ukulele Ike,") 1933, "Paper Moon"</a>
Or Rudy Vallee:
<a href="https://www.youtube.com/watch?v=hXwS7yLOYt4" style="color: rgb(17, 85, 204); font-family: Arial, Helvetica, sans-serif;">Rudy Vallee, "As Time Goes By," 1931</a>