Most likely it is because of the limited hardware across all consoles. All three of them are lacking in RAM because it is shared with the GPU. Series S also has a third of the processing power of the X or the PS5.
When the devs say they have had to move worlds to get optimization done to the point where it is playable on the consoles, they aren't kidding. Though the specs look similar to a current mid-range PC on paper, not having a dedicated GPU with dedicated memory puts some huge limitations on how well they are actually able to perform. You end up with something comparable to a mid-grade laptop with inbred graphics.