You generally want to use Party Finder for Extremes and other harder content, because they usually require coordination that is beyond many Duty Finder groups. If you're just doing Extremes for the storyline, then you can run it unsynced so higher level players can kill it in 10 seconds flat, or if you want an actual challenge then you can start a synced Learning/Practice party so that everyone is willing to learn and persevere through it. Queueing for Extremes in DF carries a good chance that people will get frustrated and vote abandon after a few wipes for a variety of reasons (little to no progress being made, Mentors unwilling to mentor, new players unwilling to learn or apply effort, etc.). Not saying it's impossible through DF, but you should have a much better time with EXs through PF.
That said, Ramuh is considered one of the hardest ARR Extremes because of the coordination required so I'm not surprised that it's still a DF killer to this day.
Good luck on your next run!