Because we suggest you setup a legal entity.

Law eksperts we talk to tell us most eksperts do NOT want to work as individuals; they should become a "legal entity".  

With a legal entity, your contracts and working relationship will be "corp-to-corp".  Your invoices will also be from your legal entity, not you.  To set your legal entity up in their systems, some clients require they have a valid URL with basic "corporate data" readily accessable.