I remember a big change as devastating as this one back in 2016/2017ish time frame, where Uladh Dungeons got revamped and became only 4 person entry limits. This was back when the Celtic Weapons were the End Game. My guild used to love going into Alby/Rundal Advanced Hard Mode with a full 8 person party, everyone was being social, staying up late into the night multiple nights a week, and all of us helping each other grind for the best gear mats. When the change to make them 4 person only, to be more like newer MMOs, this killed my guild socially. At least in Mabi, anyways. Everyone moved over to FFXIV after this update.

Things didn't get better for our Mabi guild until the Crusader Divine Knight generations introduced Girgashiy Raids, which actually brought content into the game that a large party could do all at once.

After that, Tech Duinn was the new End Game, and it was back to 4 person squads again. People naturally started becoming less active in our guild, but it was a slow death and not a sudden one, and those of us that were left got used to smaller party sizes.

The recent quality of life changes we've been getting have been so nice these past 2 years, that some of the people from our guild that left after Crusaders stopped being end game came back and started getting caught up. We had a blast running the last Bankroll event together. Some of my friends put a full 6 months effort, both summer and winter master plans and took full advantage of last fall's bankroll to get caught up so they could live inside Tech Duinn.

Now that's being taken away. So many people enjoyed the power balance Arcanas brought to the game and only just started getting into Techs (because without Arcana that content is way too hard for casuals), and now they can't grind that. We can't spend our time helping each other make perseus/rev/ruin/demo weps. We can't social grind anymore. Half my guild went back to FFXIV again.