Speaking as a younger but also older sibling, it is definetly a mixed bag. While I never was ‘bullied’ or tormented to a point I’d personally consider it serious I definetly was the punching bag for my older sibling at times. Likewise my younger siblings were to me, although I can’t really say nowadays why I’d ever acted that way towards them.
On the other hand, even while punching down, as the older sibling, during our childhoods we were always protective of our younger siblings when it came to outward ‘threats’. It was like the older sibling was the only one to pick on the younger one. If someone else dared to try, it was up.
Nowadays as adults we tossed the ‘bullying’ aspect of the relationship aside completely. The protective part remains and grew stronger. Everyone protects anyone else, should the need arive.
I’m not a parent yet, but my family grew by some nieces and nephews in recent years.
And while I’m not around them all the time, when I am, it definetly feels refreshing to hear their points of views or have them ask questions about things that I, as an adult, take for granted.
And more often than not these questions lead to new knowledge for myself, when we decide to look for more than just the surface level answers.
So I’d agree with the two listed ‘benefits’ of yours, if given the chance children can be a great opportunity for learning and growing as a person. One needs to make use of that opportunity though. I see a lot of parents dismiss questions with ‘obvious’ answers or even getting somewhat annoyed at times.