They should do this to replace giving our licence or passport numbers when signing up for things that actually need to verify who we are, like with banks. Would reduce the chance of our data being compromised in a breach.
It should not however be used for anything like social media or porn sites. Random sites do not need to know who we are.
Characters needing to talk “privately” when in a location with others. The solution is always to take a few steps in one direction. They’re still clearly within easy hearing range of anyone who isn’t massively hard of hearing. Yet apparently the other characters in the room all just go temporarily deaf.