There are a lot of examples in the # on twitter from the data mining to prove this point.
The reason this is trending is this translated quote from an interview with Famitsu that contradicts the findings of the datamining:
Considering the quality of graphics in Pokémon Sword and Shield, it certainly would require considerable time to do that kind of work for every Pokémon.
Masuda: I was personally sad about this decision. Of course, had it been feasible, I would have liked to make it possible to bring every Pokémon into the game. However, this was a choice we needed to make sooner or later. In the end, we had to choose quality.
Ohmori: Masuda and I discussed this issue a great deal. Even for Pokémon Sun and Moon, it was quite a difficult situation (to make it possible to bring every Pokémon into the game). Now that we are moving to the Nintendo Switch and remaking the models from scratch, we had to make some kind of choice. That said, despite the limitation on the Pokémon that can be brought into the game, the game's wild areas, story and other content is quite rich. I believe that players will understand that when they play the game.