What do you mean, they "may not"?
Code:
Megalopolis Region 12
Metropolis Region 10
Dense Urban Region 8
Urban Region 6
Sparse Urban Region 5
Developed Rural Region 4
Rural Region 2
Pastoral Region 1
Enclave 0
Tiny Island 0
Wasteland 0
So unless a minor has five major city states (metropolis)...
Hungary only has three states. We saw on the video one is Alfold, urban region with 6 unlocked slots, 4 already built at the start of the game. Transdanubia, urban with 6 slots, 4 already filled. And finally Northern Hungary, dense urban (it includes Budapest) with 8 slots and all 8 are already filled. This gives Hungary a starting amount of 16 factories and the potential through construction alone, only to build 4 more, for a maximum of 20. Plus the factories from NFs.
With his current research level, Daniel was going to take just under 2 years to build those 4 extra factories, because he chose military factories. Civilian factories cost twice as much construction, but each one he constructs reduces the time taken for the next one. So that's about 3-3.5 years to build 4 more civilian factories.
But then he trades away some of his civilian factories to get some steel, immediately reducing the civilian factories he has available for construction. He doesn't show the effect on this, but it's going to make building the 4 extra military factories take over three years.
Lower Austria state (with Vienna) is dense urban 8 slots. As you would expect, Austria's mountains should reduce it's industrial capability, but we don't see exactly what slots were in Upper Austria and Tyrol. Except that on annexation his total number of factories increased from 17 (he had completed one of his own factory constructions) to only 26, so 9 factories captured from Austria.
He gained only one civilian factory for construction, probably not because there were 8 military / 1 civilian but because most civilian factories in Austria had to be used for his increased consumer goods demand. But he then immediately traded two more civilian factories (making a total of 4) to get even more steel for his war, before realising that he has more steel than his factories can use, and reduces it back to 3 factories buying steel. Overall that means EVEN AFTER CAPTURING AND ANNEXING AUSTRIA he has no more civilian factories available to construct stuff than he had at the start of the game. His early wars means he has to put as much effort as possible into military factories for infantry weapons, rather than building up his industry. You see he also choses to go down NF branches to get things other than the Construction Effort free factories.
Nevertheless, his conquest of Czechoslovakia brings him to a total of 47 factories and almost to being a major nation.
There's no doubt some of the larger minor fascist countries should be able to get enough factories to reach 50 factories by conquest. But they can't do it within their own borders. And it sends WT to a point where he is now risking war with the Allies. Plus his choice of NFs so far means he is still over a year from one extra research slot, never mind the second.
Democratic/neutral countries, even those starting slightly larger than Hungary, will struggle to get anywhere near to major status early in the war just by construction and NFs. Their number of states, and that some of these will be rural, prevents them expanding too much.
As a plausible thing I don't see an issue with Hungary-Austria-Czechoslovakia having the research slots of Germany. But it looks like it will be 1939 before that happens.
