There is no valid reason to forcing you to keep a collected card except possible financial gain to SDS.
If you can't exchange or quick sell collected cards, then you have to find a new way to get stubs to either buy the cards to exchange or to have the stubs available. In a lot of cases, what's the fastest way to get stubs? Buying them.
Yea you can flip cards for profit, but that takes a little while to get the orders up and then wait for someone to sell you the card and then sell the card yourself. Doesn't take forever but in comparison to being able to have hundreds of thousands of stubs available in minutes, it does take a lot longer.
If I collect a 30k diamond card, I can no longer get that 30k back in stubs. I can either get 5k back in stubs or points in an exchange.
Now in 20, I can't get anything back for that card. Rewards are not better for collections this year, and there was no trade off that made this better for us. This only benefits SDS.
This is the way a ton of us have done it for the past 4 games, no reason it should have changed
The only way it should be seen on SDS's part is that it's possible lost profit that they can now take advantage of.
The whole IRL card collecting explanation MAKES NO SENSE.