A quick reductio for the “three times” framing is to notice that if, having already decided to buy a phone, you were to convert $250 from your bank account into phone-purchasing credit, then the prices change to $500 and $0, and the question changes to whether the more expensive phone is infinity times better. That version of the question makes no sense, so dividing the two prices by each other don’t make sense either.
A quick reductio for the “three times” framing is to notice that if, having already decided to buy a phone, you were to convert $250 from your bank account into phone-purchasing credit, then the prices change to $500 and $0, and the question changes to whether the more expensive phone is infinity times better. That version of the question makes no sense, so dividing the two prices by each other don’t make sense either.