Theory Question – skipping the peppers in pickled pepper mix

This is a theoretical question to see if anyone who understands the can explain something to me.

In All New Ball, there’s a recipe for pickled onions and peppers, which is very tasty and I’ve enjoyed many times. It has raised some questions, however:

Could the same recipe be made without the peppers to get just the pickled onion? Or without the onion to just get pickled pepper? Like scientifically – based on the generally accepted knowledge that low-acid ingredients can be reduced or eliminated without affecting safety, does that idea apply here? If not, why?

Again, not planning on doing this, it’s more scientific curiosity.

by bijouxbisou