I won't say it's common, but it does seem to happen more than it should. I was thinking the same reading the article. It sounded like there may not have been anyone on board.
It certainly does not happen on my boat. There is always at least one person capable of operating the boat and calling for help should that be needed. Currents pick up, or otherwise things happen. While rare, there have been a couple of instances where the anchored boat came to pick me up. No danger, just currents were a bit stronger than expected so it would have taken a bit to swim back.
I'll never understand why some insist it's fine to leave no one on the boat in open water. I could somewhat understand in protected water, but not open.