It's done so that when the crypto bubble bursts again, the market isn't flooded with used graphics cards.
In 2017 everyone was buying GTX 10XX cards, on one hand because they actually represented a good improvement over the last generation for a change, but mostly due to the crypto bubble. Which then burst at the beginning of 2018.
Then RTX 20XX came along, which actually represented a slight drop in price/performance if you don't count the raytracing/AI cores (which to this day hardly matter in gaming), while used GTX 10XX cards were still everywhere.
So now nvidia wants to make sure cards used for crypto go straight to the landfill after the current bubble bursts.