Why are two strokes not allowed?

Often (actually, every year, every event) the question is raised "Why are two stroke motorcycles not allowed?"

Here's why:

1. No street legal 2 stroke dual-sport are being made. Yes, the manufacturers talk about it, but none are being made that are currently being sold as road legal in the US.
2. "But I can register a blah blah blah" Yeah, maybe so... but rangers hate hearing them in their forests so that's not a fight we're gonna fight. Plus, we don't want our volunteers to be responsible for verifying that some wacky semi-legal or maybe "used to be legal" bike is actually still legal.
3. There's no shortage of affordable, fast, capable four stroke bikes.
4. And if you already have a 2 stroke bike, there's LOTS of other places you can race it.
5. The old two strokes that were street legal... those are 40 years old and there are almost none of them left.