Another factor is that previously the last point update of an iOS version was always jailbreakable. So there was the long period over the summer where there was

Another factor is that previously the last point update of an iOS version was always jailbreakable. So there was the long period over the summer where there was a stable jailbreak that people could experiment with and utilize while Apple was focused on the next big iOS version. Now Apple is very aggressive about making sure the most recent iOS version is locked up and preventing downgrades.