I tend to think of the loss due to something like this as a stupidity tax which I have to pay periodically.
The same thing applies to a bad play during a game. Why did I play Card A when Card B is clearing going to destroy it? Please enjoy my money.
If you change decks frequently enough that you are talking real money you may just want to keep a spreadsheet/document with your deck codes with the mark included. I do not feel adding the additional step is worth the large amount of accumulated wasted clicking 'confirm' for the occasional saved loss. I get so tired of confirmation messages for routine things. "*sigh* Yes, please do the thing I just told you to do. If I hit the wrong button, I will live with the consequences. Please stop nagging me."
Going the other way, maybe they could add a Deck Nanny - "Do really want to include Sanctuary and Solar Shield together? You know Sanctuary prevents Solar Shield's gain light quanta ability, right?" or "You have Butterfly Effect in deck with nothing small enough to use it on. Choose one: 'Proceed as an idiot' or 'Go back and edit deck with head hung in shame'."
