That's not quite the same thing, this is specifically about the allergen itself needing to be introduced vs. avoided. The "hygiene hypothesis" as you said is more a general idea that the immune system should be exposed to a wide variety of foreign or pathogenic material in early age.

The avoidance of allergens was a deliberate thing under prior advice, and/or them being less common in the diet to begin with, it's not really a matter of hygiene or cleanliness.