Yes. Factorio has a hardcoded limit of 256 surfaces per world, so Factorissimo needs to reuse surfaces at some point if it wants to support an unlimited number of factory buildings.
Factorissimo1 didn't care about that limit and just made a new surface per factory, so when you placed your 256th factory it would just crash. Since the original code was written without me knowing of this 256 surface limit, it depended a lot on the fact that each factory had its own surface, so it was really hard to update it to support having multiple factory buildings on one surface. This was one of the most important reasons for the complete rewrite.
Now you might wonder why the max_surfaces config option is 100 by default, and not, say, 255 or 250 or just 1.
If a player leaves a factory building while his personal construction robots are still busy, then they will not exit with the player, but search for the nearest available roboport or personal roboport on the surface. If no roboport exists on the surface, then they will simply hover in place until the player reenters the factory.
Now suppose all factory buildings were on the same surface. A player abandons his construction bots in one factory building, and then he enters a different factory building. The robots notice that there is now a roboport on the surface, and they will attempt to fly over the void to reach the player. Even disregarding that this totally breaks the immersion, the robots will quickly run out of juice and be lost in the void for a good amount of time, all the while hindering the player because they keep affecting his deployed bot count so he can't deploy new construction bots.
To avoid this issue almost completely, factory building interiors must be spread out over a lot of surfaces instead of all being on the same surface.
Now the max_surfaces value is 100 instead of 255 simply because it's polite and considerate to leave some surfaces for other mods that might want to use their own surfaces too. The most obvious example here is of course Factorissimo1. If the max_surfaces value is 100, then players can upgrade to Factorissimo2 on the same world even after they've already built over 150 Factorissimo1 buildings.
