I am going to assume that the vast majority of applications are filled out by the applicants. I imagine that we don't hear from them because a) our applicants are web savvy and can figure out the Common App pretty easily and b) students are more than comfortable with hitting the "help" link when they have a problem. Adults might not feel the same way. I myself have been guilty of calling a business about an online problem without consulting their FAQs and support pages first. I imagine younger folks are apt to check the online resources first and pick up the phone only after exhausting those resources.
I'm not saying parents shouldn't be involved during application season. In fact, I think this process is a great one to tackle as a team. Adults should be providing guidance and that second set of eyes that might catch a typo or an awkward phrase in an essay. I do not think they should be assuming their child's identity online. College bound students, even busy ones, can fill out the forms. It might cut into their Facebook time over the winter break, but they can do it.
If you are headed for UVa, you should be more than capable of completing the Common Application. I would also hope that you would only allow your name to appear on work that was yours.
As always, if you have questions before or after the deadline, just post a comment and I'll reply as soon as possible!
Application forms can be tedious...but a student bound for UVa can handle it.