I'm amazed at how many times I've seen a poster refer to their child as their "best friend".
The parent child relationship is unique and to be cherished. We nurture & care for our children but our responsibility is to prepare them to be functioning adults, without our input.
In order to move from being a baby to an adult, our children need to learn things that it is our responsibility to teach them, and they need to step away from us and build their adult life. This is how life is, how we function.
There are times when we need to out in place boundaries, when we say no or have to watch them figure things out - it's part of the growing & learning process.
So to say a child is your "best friend" is to change the parameters of the relationship, to the detriment of the child.
Friendship is a relationship of equals, with some give & take as people's circumstances change. Some friendships are lifelong, some are for a period of time (Uni, small children in common, career friendships etc)
AIBU to say that if you see your child as your "best friend" then you are doing both them and you a disservice?