Just a thought, but I think that there has always been family members that have moved away from where they were raised. Think about the people who came over from Europe to America & didn't go back.
Back in the 1600/1700s, there wasn't any mail service. If any letters made it back, the only chance would have been when a new boat arrived & was going back. Paper & ink I imagine was a rare commodity & you would have had to get someone like the captain to agree to see it made it to where it was intended to go. Same from Europe to the Americas.
Probably the 1800 wasn't much better until later in the century for mail. By then, in some families, many generations would have passed & no may not have remembered or been told where the family was at across the sea. Recently arrived families may have had better contact, but eventually that likely ended.
I think that it seems more prevalent today because we do have phones, mail or e-mail to contact one another that makes it easier. But then, everyone has their own life & reasons for moving or for whatever reason, don't keep in touch.
We still get together at the holidays, but as the kids have grown, some have moved in because that was where the job took them. Even if they are still in the area, a few work at jobs that are 24/7/365. They don't have the opportunity to be off on the holidays because the don't have the seniority for a vacation day or it wasn't on their scheduled day off. I didn't take off on holidays when I was scheduled to work even though I had the seniority to do it. I didn't want someone else to be ordered in early to work or over to cover my shift & take what time they would have had from their family on that holiday.
Even early humans moved around the continents on their own two feet & may very well have left family behind doing it. Before the time people started to sail around the world, I understand that family groups had the opportunity to remain close. But then, I'm sure that family squabbles took place then & people could have decided to not talk to one another & not gather with the rest too.