Do you like sleeping with or without pillows? I know some people who can't be bothered about using pillows to sleep because with or without it, they can sleep very well. On the other hand, some people can't sleep without pillows while others would have neck pains if they use any kind of pillows to be sleep.
I think that this depends. Some people can sleep without pillows. Pillows offer good support to your neck. In some cases, pillows are useful. If you sleep in the wrong position, then in such cases, you may suffer from body aches.