Giving out your last name on the internet is a lot bigger of a deal than giving out your first name. If someone has your last name, they can find out pretty much anything about you. I’ve found multiple random internet people’s home addresses (I’m not a stalker I promise!) just by doing google searches with their names. Imagine if I was actually trying to stalk them.
Also, personally, I kind of wish I hadn’t given out my last name. Oh well.
My online footprint is so freaking massive - if you try you can figure out just about anything you want about me. Address, phone number, emails, the college I go to, and a lot more.
The US has really good GIS data in most places so if you know someone’s full name you can search and find their address easily