Pretty much this. We may have lost roughly half the national dex, but the remaining half of the national dex is still a freakishly huge amount of mons. People need to stop pretending that having 'only' 400+ Pokémon (which is still 100+ more than the Sun and Moon dex had to offer!) means that the games are lacking in content.
It’s not really more than what sun and moon had to offer because you could trade the rest in from previous games