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I've only seen confirmation of this regarding wild encounters:
"One thing we didn't originally intend to implement in Pokémon Sword and Pokémon Shield was having Pokémon roaming around in the field. After Pokémon: Let's Go, Pikachu! and Pokémon: Let's Go, Eevee! were released and we saw how popular the feature was, we worked hard to bring it over to Pokémon Sword and Pokémon Shield for a lot of the Pokémon and adjusted the balance of the games to make it work."
I don't think they could have implemented the Wild Area in about 7 months (from LGPE's release and E3 2019). Oddly enough, I guess they thought a Wild Area without random encounters was a good idea? It boggles the mind.
Remember that there were no random encounters in the February trailer. They obviously needed more time.