Well firstly let's kill the myth that Nintendo games keep their price because they keep selling.
Plenty of Nintendo releases pull modest numbers, for every Animal Crossing there is a Yoshi's Yarn, Arms, Xenoblade, Fire Emblem, pokemon Dungeons, Paper Mario, Labo, Pikmin, Hyrule Warriors, Metroid etc. Particularly prior to the Switch these niche 1-3m selling titles made up the vast majority of Nintendo's output, hell even mainline Zelda would peak at 5m (windwaker, Skyward Sword, majoras mask etc). Still their pricing policy remained what it is. The sales tactic is based on their principle of pushing the value of their titles/brand + maintaining high profit margins from this, regardless of whether the title sells 2m or 15m. It's a tactic which works for them especially as third party interest in their platforms is very low. Its the reason why the Switch has record sales but very few million sellers not from Nintendo.
Secondly, who said people do not wait to buy Nintendo games? What's actually very typical is that their sales start off slower but just maintain healthy legs. By definition that is people waiting. I think the key difference is years down the line every big playstation game has been replaced by similarly big genre competitor or successor on the platform., Hence why you see them at reduced prices, fighting for visibility whilst also making room for new games to succeed at full price.
If there was only 1 call of Duty, 1 Assassins Creed, 1 Fifa released each gen they would be selling 20m+ on playstation alone and likely maintaining their price. Less saturation would mean less need for people to cut prices to compete next to them as well.
Sony and many 3rd parties could do the same but considering there are literally 4x more retail releases on playstation every month, it wouldn't be healthy for them or 3rd parties. The same principles of "Must Have" software exist on playstation/xbox but it's just spread through far more releases in a year... looking at big releases this year on PS4 we've seen Final Fantasy VII/TLOU2/Ghost of Tsunami/Marvel Avengers/Fifa and coming up we'll see Assassins Creed, Call of Duty, Cyberpunk, Spiderman... All bar Marvel will be 5m+ sellers by early next year.
Nintendo however will likely end the year with only 1 title released in 2020 which sales will pass 5m (Animal Crossing). In one quarter we're seeing 4x the same number of big releases than Nintendo has managed its whole year. So Nintendo's flagship titles will sell more on average but there will be far fewer of them.