I think it comes from perspective. The coaches who come across as "dismissive" of parents who are "learning" rules and deductions on this board tend to be optional coaches. And, this sounds harsh, but they don't care what your kid is scoring in compulsories. My observation is they want your child to master the basics, get competition experience, and most importantly GET TO OPTIONALS. So all they are saying is, "if we don't 'care'.... Why should you?"
As a parent, I get it, I cared very much, and learned the rules, but looking back from this spot at L9 to those Old-L4 scores, they are meaningless. It was more meaningful, to my dd goals of today, that she continued to progress, gained the necessary skills and learned how to compete. And I take to heart what Dunno has stated on this forum before... Scores don't matter until L10.
I'll never forget what an awesome, well-meaning coach kindly said to me after my dd's first (old)level 4 meet 5 years ago. One of my dd's teammates did phenomenal and I was marveling about that with this coach. The coach said matter of factly, "Nobody cares about L4.... Nobody". I have giggled about the harshness of this line over the years, but now, from my L9 perspective, the meaning has become more clear. She wasn't saying, "we don't care about your kids competing L4". She was saying, "don't sweat the small stuff."