Your argument just doesn't work. Sorry, but it doesn't; credit isn't an "all or nothing" deal, but depends on consent; some people will ask you credit for specific things, like asche, some people won't, like the many designers who did the tools you work with, or that paved the roads you traveled so you could go get it, or the doctor who attended your birth. If you truly had to credit everyone involved in your card, regardless of consent, you'd have to credit everyone who was ever even slightly connected to you and the fact that you're here today to make that card.
As I said, it's a matter of consent; people like asche (and the rules of pokebeach, when it comes to using art) want to be credited on the cards; that's their prerogative. The designers don't care if they're credited in our silly little cards, they're already credited in the opening screen of Photoshop, and that's what they want, because that's what their resumes need. I doubt asche has "made pokemon card blanks" on his resume, so what he wants to get out of it is social recognition in a specific social field, not work, and that's fine. It's ultimately his decision, not yours, and if you ignore it, I think you know with whom will the rest of the people who might care about something as silly as this will side.
I understand not wanting to be bothered with credit; I had that problem my first time in CaC (and my second, because I included the border of an HGSS card in my own blank, since I hadn't finished my own borders yet), because, to us it doesn't matter much, but it does to them. Getting away from that mess was part of the reason I accelerated finishing my own blanks, the other being that I was doing them anyway. Now I don't have to credit anyone, but not because there's nobody to credit; it's because they don't want or ask for my credit.
But as far as my sympathy goes, you are being pedantic, and rude. Anyone can make a mistake with blank credits, but there's no need to escalate this to a discussion about copyright and creator's rights, when the site's policy itself makes it clear enough.
It's the spirit of the law. I don't see much the point, really, as long as you don't claim or imply to have made it yourself, but fine, it's a sensible rule nonetheless.