My older daughter had a Winnie the Pooh cup and plate when she was a toddler. She used it for most of her meals and got to the point that if she didn’t get her food on it she would refuse to eat.
We asked her pediatrician about it. She explained that when kids are that age they control almost nothing in their lives, so when they find something they can control they latch on to it.
When I find myself insisting on my way about something trivial I think about that cup and plate and ask myself if I’m frustrated about a lack of control in some other part of my life.