The first guild I ever joined in an MMORPG was in Final Fantasy XI, and it was made up of about 40% new people from the game in question and 60% an existing guild that had migrated over from EverQuest. This made a certain amount of sense, since the latter game was not all that different in its base assumptions and gameplay. But I did not stick with that guild for the entirety of my career in FFXI, and I certainly didn’t join them in any future migrations. For all I know there were several more. It was decades ago, cut me some slack.
This is normal to me. I have never been a part of a group that has migrated, en masse, from one title to another. But a lot of people I know have done that, some of them even in the same group as they were in back in the before times when MMORPGs provided a brief distraction after hunting the mammoth. So have you ever been part of a large player group migrating to a new MMORPG?