Likely because as the Twitter thread demonstrates, most non-geeks don’t know what Find My is or how it works, and they don’t care to learn about it.
Since Android and iPhone make up the vast majority of the smartphone market, and modern devices on both sides have "Find My" style features, it feels like something they aught to know about.
The police know to look for a serial number on a drone/bicycle/vehicle so why not the equivalent for phones?