Even today the biggest benefit of baby slings is the safety it provides to a child. Modern technology offers many baby alerting mechanisms to connect a baby with its parents. There are two-way baby monitors through which the mother can coo back if a child is whimpering, and there are baby monitors with video facilities through which parents can watch the baby. Still, the security provided these provide nowhere near the security by a baby carrier, which allows the parent to keep the child literally bound to her. When the child is safe, the parent too will be tension free and in good spirits by extension.
Another benefit is the hands free option a baby carrier provides. If a child is to be carried around without a sling, you will need both the hands to support it. This position obviously leaves you unable to do any other job. A slightly older child can be held in one hand and the other hand can be used to attend to small tasks. But when the left hand is carrying a child, even the right hand will not be able to work at full strength. With babies safe inside baby slings, women even manage heavy works like scything in the fields, or herding cattle, or breaking rocks.
The convenience scenario is not the only positive aspect of carrying a baby in slings. The set-up of holding a child in hand for long is against the principle of ergonomics as well, especially when it is carried on the hips. When a baby carrier is worn correctly, the childs weight gets distributed uniformly across the back or front so that the wearer is unlikely to have pain in the arms or shoulders, which could result from carrying the baby in arms.
From the ergonomics point of view the Ergo baby carrier is a distinct advantage. These baby slings are designed to carry larger baby weights and can be used for slightly grown babies. Ergo carriers come with many attachments like weather cover, waist extender, doll carrier etc. A weather cover is for covering the baby if it is too chilly, and a waist extender is for extending the baby carrier to fit more heavy-set parents. And manufacturers offer even ergo doll carriers for pre-teens to live their games fully by carrying dolls or teddy bears in it.
Being together with the parent in baby slings aids faster mental development of the child as well. Continuous proximity to adults exposes a child to more outside sounds than it would be exposed to inside a crib. So the child will pick up the spoken language faster as it will be exposed to adult conversation more frequently. A baby who spends a lot of time in a baby carrier with a parent will also be more easily alerted to sounds like animal sounds, or vehicle sounds, or whatever sound is more prevalent in the surrounding where it is carried around, as well as the colors of nature. When he is alerted easily to sounds and sights, he will learn to respond faster to them.