The early lineups are only needed because there are a lot more people than space to put them in, if the people have particular preferences about where and how they camp.
When I first started going, the "civilized" people all wanted to camp in the RV park - now by tradition called the "Walnut Grove." It's adjacent to the fairgrounds and stadium, has electricity and water for those with "campers" and/or who need those amenities, but can only hold about 800(?) "camps." If you want to get space, and/or one of the 700 or so "hookups" there, you've got to get in line to be among the first few hundred to get in. You might find a space, but not be near a hookup, but more likely you'll find a hookup with no place to park where you can access it.
The "Pecan Grove" where we camp and have camped since 1985 has only about 80 electrical hookups, and three or 4 water taps. If you want a space in a particular area, and especially if you need electricity and water, you almost have to get within the limited space "in the oval" formed by the park's main roads. There are about 30 electrical outlets "outside the oval," but only along a short stretch of the oval road. Those usaually are taken by early arrivals within the oval who run their power cords back in across the road. There is NO WATER within at least 100 yards for anyone "outside" the oval in the Pecan Grove. Two thirds of the land area referred to as "Pecan Grove" or "South Camp" is outside the oval.
It's only been three or four years that they've allowed camping on the "ballparks" - referred to now as the "East Camp." This area is nice and flat, at a higher elevation so it's reliably dry, but no campfires or other "open flames" are allowed (even for cooking), there are fewer than a dozen electrical hookups near the grandstand, and again, NO WATER, and ABSOLUTELY NO NATURAL SHADE.
If one just wants to "be there," and can get by without electricity and water, there is no real problem finding a place to park it all until the very last day or two before the official start of the festival (a week after landrush). If you need more water than you can, or are willing to, lug by hand to your camp, you need to be there within the first day or two after landrush.
If you need an electrical hookup, as we do to run all our medical devices, you'll have to be among the first fifty or so into the Pecan Grove at landrush, and that means you'll need to be in line at least within the first 4 or 5 days that anyone is admitted to wait in line.
It gets even more complicated if you're part of a larger group that likes to "camp together;" and several traditional "Camps" have over a hundred regulars attending every year. A couple of them run over 300 people, and there are no "space reservations" to be made to keep them all assembled. It's be there, or go camp somewhere else.
A few people do rent a motel, or camp at the nearest lake, but to get a motel room reservations must be made more than two years in advance** and it's about the same at the accessible parks within any reasonable distance. The nearest commercial RV park is about 50 miles from the festival, and is usually booked nearly a year ahead.
** A few years ago, we were unable to book a space to board the dog for the week when we called 11 months in advance. They've found a few more places that theoretically can keep your pets for you, but we haven't needed to check what the lead time is - or whether they're places we'd have been willing to leave our pet with.
If you're alone, with a tent or small camper, or even with a group of a dozen or so who can all arrive together, there's a place to camp even if you come in at the last minute. If you need hookups - especially electric - or if your group is more than a few and people have to come in over a period of time, it will be difficult to keep them all together unless someone, preferably a major part of your group, can get there early.