Ok well I will try and explain it, because I have applied methods like this before when working with photos , to apply some of the "smoothing" algorithms to photos or low res photos, without getting a very wide deep smoothing.
it goes something like this.
Here are your pixels in the usual resolution you would be viewing in. In dire need of anti-aliasing or smoothing the jaggies.
On one side here we have up-scaled the image to 4X then applied the same anti-aliasing algorithm
It is important to note that as a stupid computer , I cannot just bend the black to the white (changing the amount of whiteness), but also have to bend the white to the black (balancing the equation :-) . I am applying a mathematic matrix blindly to where I was told to apply it. Although the video card algorithms are very sophisticated and they actually are not as blind as this.
Observable example of the balance in games, You wouldn't want your fence to disappear into the sky, and you don't want your sky to become the fence, so any adjustments have to apply to both sky pixels and fence pixels more equally. Also an example of ways that the video cards and game engines upset this balance to get a best picture going still with that sort of tough details.
At some point this all has to go back to the display resolution, where it will be the lower resolution, and after having a wide array of items to adjust around, that extra bunch of pixels will now be perfectly blended into less pixels.
(well it wasn't the perfect color for that blend, but I didn't do the math)
And as you can see it looks terrible again in the display res.
On the low res side we have this vast effected/changed area as we bent all these pixels toward each other (both the black and the white) and have a huge swath of smoothing because we were only working at a low resolution.
On our High res side we have instead obtained a perfect balance set of pixels mixing together 4X pixels that makes a smaller smoothing area. so the High res side finds the pixels that would smooth this all out really pretty, but doesn't leave a big blurred up mess.
Because (again) we have to bend way more pixels , to maintain the balance of blending one to the other , If we up-scaled first we can create this bending blending at a smaller scale, still maintain the balance of bending one to the other, and the final result is less effected pixels, same jaggie hiding.
When you compare the 2 methods side by side using games, the difference that is achieved with what seems like a lot of extra work is not that much. Same thing when I am processing photos that will be used back at the lower res, it is a lot of extra effort for me and the machine, and the results are just barely better.