What is complex about it? That sounds like an excuse for not making an actual argument. There are lots of excuses when it comes to not granting statehood but they are invariably self-serving. They pay taxes but their votes don't count. We had a revolution once where that was a major factor. Puerto Rico is near the median in terms of state population. For over two down decades it has been clear that a majority of Puerto Ricans do not want to remain a territory.