What was the reasoning behind the extreme modes of Leviathan and Thornmarch to be restricted to same server Party Find? Why weren't these two extremes released fully into the Duty Finder when Turn 1 to 5 of Coils had? Will Ramuh Extreme be released in the same way and why?

I love extreme primal fights and I don't have the time to sit waiting for Party Finder (sometimes it can take all day to get a good group), I felt like FFXIV got a lot smaller when I could not Duty Find these primal fights. I am scared that this can happen in the future and I am upset that it took so long for these extreme modes to be released into Duty Finder.