First, you are showing Southern section bias by referring to a State tournament

. Some sections are not organized by state, instead there are areas or districts that are not state aligned that advance to Sectionals. But in Southern a State is a District so we'll assume you are asking about district level playoffs.
In my experience, you will see a mix of teams at Districts and some will have players that are going to be bumped up at year-end. That is more or less to be expected as the teams that make Districts are the best teams from their local areas/flights and are often put together to make a run in playoffs so have stronger players to begin with, and then especially at lower levels but still even at 4.0, players who are making a run at playoffs often practice and get lessons and improve which pushes them into the range to be bumped up.
Now, there is a different between "some" and "nearly all" players on a roster being this high. I would say it is not common to have the majority of a roster this high, but it certainly does happen as you can see from the Nationals previews I recently posted on my blog. At some levels, all or nearly all of the teams that are top-40 in the nation have top-8 averages at or over the top of the range for the level. Now, these are just the top-40 teams across the country, and assuming an even distribution across the sections that would be just 2-3 teams. But the distribution is not even, and Georgia does tend to have more than their allotment that are rated very high.
Now, there is a bit of a reason for this. Yes, as much as I dislike seeing it happen, sandbagging does happen and it contributes to players "improving". But in addition to that, Georgia has early start leagues and teams that just played Georgia States (or are finishing up today) may have started league play around a year ago, and players on these teams that are bumped up can continue to play on their team. So you may have a 3.5 team that started play in May 2017 and had 6 of 15 players bumped up to 4.0 at 2017 year-end. Per Southern/Georgia rules, these players are eligible to continue playing as 3.5s on this team through Sectionals. In situations like this, you can see why Georgia States has such strong teams and Georgia shows up high on my top-40 lists.
Now, these bumped up players will not be eligible for Nationals, so teams from other sections thinking they'll have no shot at Nationals, fear not, you won't see those Georgia teams, at least not their entire roster, in all likelihood at Nationals as some players will not be eligible if it is an early start team with bumped up players.