Based on what I have seen I have to agree. I work closely with families of all shapes and sizes and also I have friends and school parent acquaintances with differing family sizes and set ups.
The larger families all seem rushed and stressed. Most seem to be just getting through the day rather than actually enjoying it. When I'm in larger families homes it's often chaotic and messy and the children are often struggling in one way or another. I see parents struggling to get lots of children to do this that and the other, and toddles are being pulled along while mum fights with an older child and tries to push a pram etc.. I have observed a lot more behaviour issues in children of larger families. They get less attention and financial resources, such as holiday and clubs as well as help with uni etc
I'm not saying it's true for every single large family on the planet but it does not appear to me that the children are getting everything they need. They seem to be pulled along for the ride rather than fully embraced.
I know parents of large families will disagree but of course they will. I know some adults will say they loved having lots of siblings, but they don't know any different and can't know life where they would have had more time and experiences and know how they would have liked that.
Parents of larger families will say they have so much time to spend with each child etc but I really don't see that often and I really don't know how that is possible. Each and every day I spend quality time with my dc: talking to them after school, taking time to listen to them, doing homework and reading, meaningful bedtimes and being present at their clubs, assembly, events, getting to know their individual strengths and challenges and what they like. I volunteer at their school and activities to be involved in their lives. Cooking separate meals and attending appointments and making sure I can fully focus there. Knowing which child needs what on which day for x day at school. Financially too: allowing them freedom to have the best and extras such as spur of the moment cinema with friends or just being able to take them on expensive experiences or spontaneous shopping trips when they are having a rubbish time. Taking them out one on one when they have had a rubbish week or even as a celebration for something. I have one who has had the opportunity to compete at national level in her sport which has meant lots of time and money for us. One of us is away most weekends with her doing her sport.
I just do not know how anyone could do that with lots of children. I have two with a 4 year gap. People will tell themselves they are doing that with all their children in large families but there is no way on earth that's possible.
I was one of 5 and neglected. The new babies were the focus and older kids forgotten, left to fend for themselves too young. Adult siblings have chosen to have two or less children, with two choosing none. That's the whole reason I am so devoted to my children as above. I never want them to feel as I did. It wasn't even the physical neglect and lack of experiences/finances that was the worst, it was the emotional neglect as parents were always stressed and tired.
I also agree that I get so much from my career and I can't imagine being able to work with more children.