Because I think that's what happened with my skin.

There were areas of my face where I rarely got acne, but because of how annoying it was on the occasions where I got a breakout there, I started applying benzoyl peroxide liberally to those areas daily.

In past years, I would every now and then get the urge to stop using benzoyl peroxide and see what happened. And in those times, my acne would eventually become absolutely unbearable.

For instance, I used to only occasionally get acne around my lips and chin. I eventually started making a point of applying benzoyl peroxide to those areas daily, and now I almost never get anything in those areas. However, if I were to stop using BP, I would break out like MAD, to the point where I wouldn't even want to be seen in public until a few weeks of resumed BP use to clear those areas up again.