Also very curious why it wasnt legends like Fry or Antiphon who did this first?
Well..., the basic trick here is editing the empty.v3d in Data/Maps, and you will be pleased to hear that Fry and me did try this in Feb 2023, around when we thought about how to increase the map size for Auenburg (even without AI at the time).
So your trust in the "legends" was not in vain.
We also achieved bigger maps at the time, but only via data file manipulation and we had problems in multiplayer whose solution propably requires memory injection or manipulation of the Em4.exe. The object limit manipulation is very likely also done via some kind of injection.
As I prefer to have mods deployed without any kind of launcher for multiple reasons, and resizing all models/protos was much more stable in the tests for Auenburg than editing the empty.v3d, we decided at the time to go for the rescale option, which we had already tested in Rosenburg.
As far as I have seen, EM Resource has brought this approach now further then we ever had at the time, however it is not yet clear to me whether they were able to overcome all the problems we had. But, I am looking forward to see what they were able to achieve. If it is a stable working solution, we might use it in the future.
Just to explain this 'might' : even though this inovation looks like (and is) a huge improvement from a technical perspective. I am not yet convinced that the benefit to mods is all that big. As other have commented, a 4x map is more than 4x the work, and with the low number of mods coming out right now, more work per mod won't result in more mods released.
Additionally, with Auenburg we already have a map 2x the size of Fuchsburg, and even though we did not have a problem with the object limit in Auenburg, as we used massive object pooling from the very beginning, everyone can see the performance impact of a bigger map for themselves by playing a round of Fuchsburg and Auenburg back to back. Any mod with a 4x map would have to make up for this in some way: Even if there is no object limit, the old engine is still a massive performance bottleneck, the more objects/meshes/animations there are on the map.
With this in mind, I will have to see whether any size bigger than Auenburg is still an improvement gameplay-wise, even though the developements, if successfull, are of course a hughe improvement from a technical perspective.