Eh, anyone with their own domain can use it even without hosting anything. It just takes a DNS record. So Taylor Swift can have @taylorswift.com or w/e her official website is and that’s pretty much the exact same situation as claiming domain ownership. Someone else could likely register taylorswift.boats but I think most people would realize something is off there.
My point is that she can be @taylorswift.com not @taylorswift@taylorswift.com. Also, exaggerating the number of illiterate people in the USA doesn’t help your argument. You can already be @FaylorSwift on twitter so I’m still not seeing how this is any more secure than using her actual domain that her fans may be familiar with.