>>42607737[citation needed]
Even if that were true, buying both the game and the 'exansion' for gen VII costs $10 less than buying both gen VIII games, and you have the option of selling one to buy the other, reducing the effective price even further.
Also worth considering is that by buying both SM and USUM you have two save slots while a $90 Switch game leaves you with only one, so if you ever want to play through the amazing gen VIII adventure again you'll have to either kill all your Pokémon or transfer them to Home, which will cost you money again.