The frequent feeds may be for comfort and security, non-nutritve, as well as nutritive sucking. Babies naturally feel vulnerable when alone, so making sure mom is there often may be one way to know she is not alone. It's just instinct. It's hard to work against two million years of evolution, when a baby left alone was easy prey for a predator. Nursing on demand also maintains milk supply!
During the early months, I would lie down in our family room at night with my son on the floor and nurse him to sleep. My husband and I could watch television on low volume, eat, read, use a laptop. When my son stirred I was right there to tend to his needs. It worked out very well. Once it was time for my husband and I to go to sleep we carried baby to our bed.
We usually go to sleep as a family unit, even now that my son is 22 months. He usually goes to bed when we do. There are occasions when he falls asleep earlier but it is a rarity. We have tried it and it just feels unnatural to me and more effort and stress than it's worth. It feels forced so I'll just wait until he is ready.
Many people now live in westernized houses, compartmentalized with rooms and baby is often alone. Where as in areas of the world where families share small spaces, even western cities I suppose, where people live in studio apartments, baby can sleep nearby without being alone, separated in another part of the house. This likey factors into some of the sleep issues faced in the western world that others don't face in various societies and cultures.