As a kid, I had the original Pokemon Blue for the GBC. Played it, enjoyed it, found it novel, beat it. Went to an event, got an authentic Mew (certificate is still around somewhere).

Not long after, I was gifted Pokemon Silver. Played a bit of it. Didn't find it novel anymore. Very rapidly had this feeling of "I see where this is going and I want off this ride". Gave up on Pokemon, and haven't regretted it even slightly.

I know there have been many innovations in the mechanics since (e.g. double battles), and I realize the game has a very large amount of strategy. But it also felt like the same kind of feeling I get from games like MtG ("expensive cardboard"); that also has a lot of depth and strategy and new mechanics, but the "collection" aspect feels painful in an "I can see the Skinner box" way, in ways many other games don't.

I had a similar feeling a few years later, when I played Wind Waker for the first time. That was one of the first games I intentionally decided not to 100%: specifically, I left out the picture gallery, which gave me the same "collectathon" feeling.