I love all of your examples! And they can all be done at home. Children playing their own gardens, find nests, research on them. Bees for example, research the life cycle of bees and paint them at home. And in this case, a child with limited speech gets even more tailored help to reach his speech milestones.
Children at home watch mom and dad at dinner time, how to eat how to behave again tailored conversation. Also has to take turns to talk , "mommy is telling daddy something, you can tell your story in a second"
Don't we always say, you can't expect a teacher to teach 30 children manners, its starts at home. I would frown if parents weren't modelling taking turns in conversations, how to sit at a table, wait their turn, finish a meal etc. Most stay at home moms play with there children and are YOU for their children at home. They do exactly what you do for the kids at nursery, for their kid at home.
And my problem with "kids have to go to nursery for xyz interactions (insert everything mentioned by you" is that its isn't true. Children get these interactions at home, at family gatherings, at soft play, with their siblings. Now if the child is an only child with no cousins and a mum that scrolled social media the whole day and popped her kid in front of a TV the whole day, sure, I'd begin advocating for that child to go to nursery around 3 or 4! But people always use the exception to justify a rule. It's like people saying breastmilk is best for your baby, you should try and breastfeed. "oh that's not true, there are moms who can't breastfeed or are on medication!" Well yeah if she cannot breastfeed or has supply issues, it's a no brainer.
But the average child from the average family does not NEED preschool. It is not a prerequisite to school and it's a myth that NURSERY is what provides your child with the social interaction they need. Nursery can do that, but so can the home. And in some instances the home can be more beneficial, behaviour can be corrected and redirected immediately instead of two teachers having 20 or 30 children to reprimand. Activities can be tailored to meet interests, and skill levels to make sure kids get the building blocks of what is necessary for academic performance later on. Just as an example in our home, we do not have a television, which means zero screen time. At 4 I started sending my child to pre-school for two mornings a week. Guess what a half an hour of the day was- watching a show. Other days they spent no time outside as it was too cold to take 20 kids out who will be wet and possibly cold when they return. I,, on the other hand can take my kids outside daily because i can run a bath, dress them well and we can continue our day. I can certainly tell you were more stimulation happened. It wasn't at nursery.
Equally there are instances in which I think children are better of at pre-school or nursery because of their home situation.
But what I dislike and am advocating against is the blanco statement -kids need nursery- usually followed by- for social interaction.
Your argument is exactly what people always get.