Dumb question- why does PR have a primary when they don’t participate in the general election? People from Puerto Rico can vote in the general if they have a stateside address, but there is no vote cast in PR itself.
The general election is subject to the Constitution. Primaries are not and political parties make their own rules. Puerto Ricans are U.S. Citizens and at some point the parties decided to give these citizens a measure of voice in the selection process.