Radio stations do this to squeeze extra advertising time into the show without tangibly changing the content.
Respectable professional radio personalities hate it. Rush Limbaugh was accused of doing this years ago, and he adamantly insisted he would never do such a thing. It turned out that some of the radio affiliates that were broadcasting his show were using it on their own. From that point forward, every contract he signed with the network affiliates included a provision that explicitly prohibited this sort of thing.
Thanks for the explanation! I’ve often wondered if radio personalities used digital technology to make themselves sound better, e.g., men lowering their voices to sound more manly.