https://upload.wikimedia.org/wikipedia/commons/7/74/Normal_Distribution_PDF.svg
Nobody “officially” said that the “center (yellow line) has 33% chance”. There are numerous “bell-curves”, and mapping that to a target-circle makes it interesting.
You have a small circle and a big circle. You can compare their radius and their area. If the [smaller circle] has a smaller overall area than the [big circle minus small circle] (so the “band” between outer and inner circle) but each bullet still has 50% chance of hitting the inner area, you have a (relative) “accurate” weapon, while if the area of both is the same, you have a “less accurate”.
We can compare the radius of both circles, but while that will tell us the same, it’s harder to imagine for most ppl, because we’re comparing a circle’s area to a “band’s”, which is hard to visualize accurately in your head.
The chance of hitting inside the circle is the sum (integral) of the area (between the curve and the 0 coordinate…line? I’m not native to english math…) of “the” bell-curve from one side to the middle, if the middle is the inner circle. There was nothing saying that you will hit dead-center the most with an accurate weapon, but that 50% of the shots will be inside the inner circle.
Saying that aiming with the inner-circle as “accurate” is a good idea is misleading. If you imagine the inner circle’s area as lots of circles, and every circle has x% chance to get hit, you must calculate with the length of each circle (circumference) too.
Which is better for you, standing in 1m^2 with 50% chance of a bullet hitting somewhere in it or standing in 100m^2 with 100% chance of a bullet hitting somewhere in it?
So I’m just saying that working with a bell-curve is not necessarily bad, if it’s done right. And we should have faith in the devs, we backed them for a reason.