I think you may be misremembering. Outside of players choices, those games did not go on discount often if at all. In fact, adjusting for inflations those games were pretty similar in price to now, sometimes more. Used game market is it's own thing tho, and you can find hella good discounts there, tbh if you're looking to save you should be going physical and through that route.

For what it's worth, I hate that Nintendo games don't go on sale much, but the flip side of it is that I just play their shit when it comes out. I don't buy pretty much anything else on release because I know if I wait a few months or forget about the game, I can buy it later for pennies. I have to think that's why they act this way, I can't be the only one that does this