They aren't forced to do anything, if a small enough minority of users goto old.reddit.com they will willingly deprecate it due to the cost reduction. Sometimes

They aren't forced to do anything, if a small enough minority of users goto old.reddit.com they will willingly deprecate it due to the cost reduction. Sometimes a small hit is beneficial even if it harms your customers because of the reduced operational cost. Simplifiers allow you to do a lot of things faster.