Because it's an open market, and people will buy oil with the expectation that gasoline prices will rise and therefore they can get more for the raw material. It doesn't make a lot of sense, but markets are based on human behaviour, and human behaviour often doesn't make a lot of sense.
I _can_ see some exceptions here, though. For example, if a refinery that specializes in catalytic cracking of heavy oil into light oil is down, I could imagine the prices on light oil could rise. Telecom content? Not so much, since you can't hoard telecom services.
--scott