Because you don't want to be your own registered agent.

This is out of date advice, primarily given by registered agents who often aren't actual attorneys.

Not everyone wants to have their location publicly available for the world to see. If you can be served a lawsuit, people can "serve" you a bunch of other things too.

Fair enough. For my money, I wouldn't pay somebody else to do that, but I can see the appeal for some folks.

You might want to use a registered agent rather than blasting someone's home address into all kinds of public records, or using an attorney who starts the billing clock to receive spam. And when you go for the more reasonably priced registered agents, it feels like a ticking clock until they start to enshittify.