That's entirely incorrect. This is how the systems work:
Morrowind: All areas have creature levels and loot which are static and do not change based on the character's level. The classic old-school method.
Oblivion: All creatures (and loot) everywhere are spawned based on the level of the player. Creature levels increase as the character's level increases, so that the same level of difficulty (and reward) is encountered everywhere.
Fallout 3 and New Vegas: Areas have difficulty rating ranges and creatures are locked into that range the first time a player enters the area, but the ranges do not change later on. Levels will scale with the player, but only within the constraints of the range limits. For example, if a starting character moves to an area with a level range of 15-25, that area will spawn level 15ish creatures and will be, essentially, off-limits. However, the difficulty of that area will not change later in the game, so that it will still have level 15ish creatures if you return there around level 25. Some areas are designed to be 'harder' areas, and their levels will be set several ranks higher than the character's if the character is within the acceptable range, otherwise it will be the minimum level for the area. Even in these situations though, the difficulty will not reset itself later. Most loot will be leveled, but some is static and specific to certain dungeons/locations.
Skyrim: The same as FO3 and FO:NV, except that areas reset themselves after having been cleared and thus can increase in difficulty given enough in-game time.
The problem with the Morrowind system are that (1) everything is boring and predictable with a set area progression and (2) once you've passed the level for an area it becomes very easy (and thus boring). The problems with the Oblivion system are that (1) everything is the same difficulty no matter where you go and (2) there is no benefit to exploring random dungeons because leveled random loot means you can get the same loot from any dungeon. A random dungeon is a random dungeon is a random dungeon, and there is no real point in going to different ones except for some variety in the design and the type of creatures you are fighting.
As you can see, from FO3 forward Bethsoft moved towards a hybrid of the systems used in Morrowind and Oblivion. In general, I think it has worked well, though I think they tend to err on the low side when making difficulty ranges. That said, I'm a glutton for difficulty and probably don't represent the average player in that regard. I'm perfectly happy using mods to increase my difficulty and thus don't have many complaints with the current system.
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