Sort of, but I think you focused on the wrong ends of the situation.
Yes, the ranger solo is going to struggle against Efreeti, Mummies and Dragons in the desert.... they are also going to struggle against Trolls, Oni or Dragons in the forest. That isn't the point.
The first point is that trekking across a desert (without monsters) is not something that is challenging for a low-level ranger. A level 3 ranger can easily make the trek across the desert, the same way they make a trek through a forest, the same way they make a trek across the tundra. And the challenges of making that trek never change, even as the ranger goes up to 15th level and should have harsher and harder challenges.
The second point is, if you are going to have a unique enemy type for the ranger and druid, like the Paladin and cleric have in the undead and fiends that they are specifically equipped to fight better... well... what is it? The strongest Beast in the game is CR 8, the strongest plant is CR 9, Strongest ooze is CR 10, Strongest fey is CR 10. About the only group that sort of works is Monstrosities, which do have a wide range of CRs, but are the catch-all category for anything that doesn't fit.
This is why, when the 2014 Nature Cleric or Druid got abilities specifically geared to counteracting beasts at level's 17 or so... people were insulted, because that is rather useless when you stopped facing beasts nine levels ago.
For the concept of a Nature Warrior to truly take off, we need to have nature be as deadly as the Hells. I don't think you can give specific anti-monstrosity abilities, since monstrosities are so varied, but if we focused Rangers in that direction of "this is what a high level ranger should be the perfect opponent for" then I think we would have a much easier time giving them a unique feeling set of abilities. And, keep in mind, the Paladin may be the perfect opponent for undead and fiends, but they aren't ineffective against a dragon or a Genie either. You need very very little to make this actually work.