People have often called this cutting back of the roster 'Dexit' and have scorned it as a way to sell DLC that increases the playable roster, but honestly having spent a few years getting used to it I can see the method in the madness.

Specifically it helps in the official competitive format Nintendo upholds. By limiting the pool of playable Pokemon and gradually allowing a wider variety over time, it helps - a little - in stopping the format from always being the same as last year. Inevitably things do tend to calcify with most teams being made of the same very narrow pool of most-powerfuls, but at least the calcified format of SV is different to the calcified format of SwSh, let's say.

It also feels like there's more reason to like... I have a reason to replay Sword and Shield because it offers me certain Pokemon that aren't available in Scarlet and Violet, for example. In a culture where video games are becoming increasingly consumeable and replay value is being phased out in favour of 'consume game, move onto new game', it helps to find replay value where you can.