Like many things, debate is a specialist practice in its own right. When the argument itself is the focus of competition, you have to go down the rabbit hole and compete over who is the best lawyer of the debate rules.
When you become a practitioner of many specialist topics, the nuance of the rules and exploiting them is part of the mechanics of what you do.
Edit: Moving from a long-form rant about something that a freshman barely understands to philosophical minutia that lead to nuclear war takes a significant amount of learning. And that learning is worthwhile.
K-heavy policy is kind of the extreme opposite of that, increasingly meta arguments where no one ever has to concede even a basic model of reality to the other side. I didn't like it as a debater, and I had a dim view of it as a judge, especially from aff side.
(These frustrations had me drift towards group disco and student congress after 2.5 years in policy.)
I'm comfortable emphasizing the educational goals over the civic goals because I've yet to see a high school debate round weigh in on the balance of national (or even state) policy...