I'm curious to know in what way you think babies benefit from nursery. Inspite of my points below this is not a rhetoric question. I can't think of any benefits that are purely for the baby or do you mean a happier homelike because it might make the parents' life easier? This is a very valid point of course but I was wondering if you are thinking of anything once we take the parents out of the question.
I think, there's plenty of research that shows what babies need the most (after the basics of food, shelter, safety, etc) is to feel secure, loved and mildly stimulated. This is not easy to provide in a nursery setting due to the number of children and staff turnover. It is much easier to provide at home (unless the home is abusive) or with a grand parent or any single person looking after the child. No baby benefits from having less time with their (benevolent) caregiver or having less attention. Babies developmentally dont need to socialise. If they do socialising very regularly with a small number of people is great but that is not what happens in most nurseries. At best sharing a room with lots of other kids will not harm them but I think for many babies it is overstimulating and maKes them feel less secure.
A good childminder is worth their weight in gold and I'd say better than the most excellent nursery. We had a fantastic childminder. She had 3 kids of a similar age. She didn't do school runs but she took them out every single day to either the park, stately house and gardens, farms, etc. She closed due to health reasons but even now 6 months later dc Still fondly remembers her and the other kids. It wasn't perfect. He barely napped there because she didn't have a proper set up for napping. He had lots of accidents and often csme home with a split lip. We had to provide food every day and when she was ill he had to stay at home but I do think that a good childminder fulfills what a baby or young toddler needs more than a nursery. After her we tried 2 other childminders but we didn't feel he was safe with them so now he's at nursery (and hating it).
From age 3 I think kids do benefit from nursery because of socialisation , structure, and all the craft and educational activities they do but not before that. Before that nurseries and even childminders are just a place to send kids to because you need to for whatever reason.
Both of my kids were in nursery from age 1 because I had to return to work and I have friends whose babies joined earlier than age 1 because they had to go back to work earlier. So my point isn't whether parents should use nurseries or not because most of us don't have a choice but purely about what would be best for babies if we didn't have to work.