Because of it wasn't geographic, it would end up going resident centric, and if you think the system is toxic or confusing now, imagine switching it up such tha

Because of it wasn't geographic, it would end up going resident centric, and if you think the system is toxic or confusing now, imagine switching it up such that your representatives seat was assigned to you like a Social Security Number, and followed you through life. Also imagine that seat's occupant's job, trying to represent a bloc of people sharing little more than an accident of being born in a particular jurisdiction at a particular time, that have spread hither and yon with no geographical anchor to point to and go, "that's where the stuff is happening that I'm here on behalf of". Physical locality was the primary social constraint when the government was architected. I honestly have a great deal of difficulty imagining any other way of doing things that would make even a lick of sense in terms of information propagation.