Parents held sway over their children because so much of life was dependent upon the family. Domestic help, help during food scarcity, help during a housing crisis, etc.
Today the government provides much of these services, but usually to a lesser extent. The result is the destruction of the power of the m/patriarchs, the replacement of the family by government, etc.
On the bright side, you can now walk away from abusive families. The more families are exposed, the more we see how many are messed up.
But on the downside, your average matriarch or patriarch was probably a better parent than the government, and better positioned to exert social pressure needed by often wayward children.
and then when they search in Linkedin or Facebook and your name pops up?
Thats my point. You have to actively block or hide from them and/or explicitly tell them no contact.
In the past you didn't have to actively hide because even if they knew where you lived and your phone number it was too expensive to do anything other than send the odd letter.
Yes in the past their would be less avenues for them to get back in contact if you went away, but that going away would be much more expensive for you too. E.g. in the past, people frequently died during such journeys. So costs were high for both parties.
So given that the costs of breaching the boundaries is lower, but so is the cost of making them, the solution is still just building them higher until it's infeasible to breach them.
I'm not talking about the 1800s. I'm talking about the 1920s-1970s
A three-day bus journey for a gay man moving to San Francisco or New York is not a big ask. But his parents aren't going to come visit or expect him to go back for Thanksgiving each year.
These days with cheap phone calls, facebook and cheap flights mere distance won't stop the contact.