Here’s what a native of American English answered me on the topic of ending a sentence with a preposition:
[color=blue]If you’re writing or speaking formally, avoid ending a sentence with a preposition: it might not go down well with some of the more stubborn and pedantic of your audience. But the fact is that this is really a non-rule imposed upon English by unwise grammarians of the past who thought English should conform to the rules of Latin.
So my guess is that this rule is old fashioned.
