I will also state that for the card companies, they are doing this to add "value" to their packs and if so, then you need to come up with a way to show the value is added. That is another reason why the stamping is needed in their eyes so they can show the value.
They also purchase these cards on the secondary market, usually from a specific dealer or two or so, and again that is a cost.
For them, the stamping on the cards makes sense because it shows what product (s) the cards are included with. And frankly if you don't like the stamping, there are tons of those 1971 Leader Cards with no stamping so just get one of those
And I'm sorry for those who don't understand some of the logic from the card companies point of view (and I talked to them back in the day about that) including what was in my opinion, the debacle of the 1991 buybacks.
But if I'm a card company and I purchase some 1982 Topps Card sets to put into 2022 packs (40th anniversary) I'm going to ensure the collectors know it is a special card. I will also state that either Cal Ripken card, because of the value and possibly the 1982 Topps Traded Ozzie Smith card would NOT be stamped because of the book value. That's what I mean by a market cap on stamping the cards. But if I get a 1982 John Tudor card with a stamp, I've just added to the value and have no compunctions about putting that stamp on that card nor purchasing it as a collector
And to repeat, if you really don't like them and have some, I'm happy to pay 10 cents each to take those cards off your hands
Rich