They have been so overused that many strains have become resistant to antibiotics.
I did my high school science fair project on the over use of antibiotics, and how bacteria become resistant to antibiotics. That was a long, long, long time ago, over 40 years ago. Oh, I went to the state competition and got an honorable mention. Back then. Over 40 years ago.
Think about how much the scientific community has learned since then. And some of them still keep peddling BS because it helps their bottom line.