Using caps lock on the internet is considered to be the same as yelling. You can accidentally hit the caps lock button though. Imagine if your vocal chords could accidentally get stuck on yelling mundane comments at random times.

It would be like you're at the store buying cheese.

"How thick would you like it sliced?"

"Oh, I think THREE SIXTEENTHS OF AN INCH SHOULD BE FINE!!!!"

"Why are you yelling? Just calm down."

"SORRY!!! MY VOCAL CHORDS ARE STUCK!!!! TAKE CARE NOW!!!! BYE!!!!!!"