Yes you do have a point, but as long as 3 different schools go onto states then it doesn't matter, because states decides who goes to nationals. So who cares, besides maybe ego and confidence, what the team places are at regionals if 3 teams can still go on to states. It's not like winning regionals gives you bonus points at states. There are no B teams at states to lower and boost teams so in the end B teams don't really effect who's going to nationals and who isn't.
I understand where you're coming from, you can't agree with me because if it were that way, you wouldn't be doing S.O. Everything would be simpler if it were just 15 people per school, even the whole alternate stuff, whats the point of that? There are no alternates at state (this year at least) and I don't know about nats. If someone can't compete for whatever reason, you can throw in an alternate, but they're gonna fail anyway (unless that person happens to know a lot about that event and was studying for it, but that's unlikely).