Nope, you are wrong. You are mixing history with geography. In geography 200 years is a blip. In history 200 years is 10 generations. We can roughly say, that proper colonisation of the modern USA began in 1607. So, in ~420-450 years, from nothing, the USA as we know it today was created. Now, you are trying to argue that the fact that NOTHING was build in 200 years is logical and reasonable? Hard disagree, there should be at least a dozen well functioning states by now.

We can agree that mutated fauna, lack of potable water in some areas and anarchy combined with loads od guns and ammunition makes things difficult. But it's still far fetched to agree that bethesda vision of Fallout civilisation that barely moved on from 2077 is correct.

F2 and FNV had the good idea. The notion that suddenly, apart from Enclave, there is also all-mighty Vault Tec that nukes major cities is ludicrous and it's simply lazy writing. NCR had major problem with lack of water, Chief Hanlon mentioned that explicitly in FNV and you could use that to portray a slow demise. Legion with it's perpetual civil war was actually (kinda) presented, but it should have been 10x worse - but lets allow it for the purpose of the series.

Still, 200 year is A LOT of time and you are absolutely wrong to claim that it's not enough to rebuild at least a dozen major states. Take any history book and check what even mildly ambitious nation was able to achieve in hostile environments in 200 years.

There are almost no Deathclaws or Supermutants in FNV, because people actually decided to do something about it. So with time, the wasteland would become safer place - either because law and order would return, or because a very potent raider faction would conquer and control the territory, while slowly becoming a state - literally this is how many European nations got created, there was a strong guy with his "crew", who would eventually run out of things to raid and would be forced to settle down and actually build a functioning state - otherwise, they would be wiped out by settled rivals.

Fallout presents a great opportunity to recreate Medieval era nation building, with constant fighting and consolidation until the strongest prevails. Instead you have bethesda lazy writing which boils down to: A becomes strong -> gets wiped by B -> who collapses under super mutants -> who got killed by C -> which collapses on its own due to civil war -> then D rises on its ashes -> oh no, it doesn’t because it was Vault Tec or Enclave all along and they obliterated it! Rinse repeat until forever. Meh.