That was the attitude as I perceived it.
Just Say No. :-)
Cite a few examples. By the same token, someone with a Wizardly concept should be able to sling heart exploding curses, since if Victor Sells could do it, he, as a full-blown Wizard, most certainly can. Someone with a Marcone-esque concept clearly doesn't have to check his Resources to see if he can acquire Microsoft, it's obvious he's filthy rich - so he can, right? A RCI/WVC with a High Concept of "Friendly Neighborhood Vampire" clearly doesn't need to check if he can resist Hunger, of course he can! He's friendly!
No, you don't get to do that without the rules or a roll(unless it's uninteresting background that doesn't need to be rolled). This is
precisely why rules for an RPG exist in the first place. So that you can have an objective standard of what each character is capable of and so that you can have meaningful interactions with the 'virtual environment' created by the GM. If this is gone, then games devolve into something similar to a child's game "I shot you!" "Nuh uh" "Yes I did, you're dead!" "No, you didn't!".
Or, in other words, there's a reason there's a "G" in "RPG". That's the Game part. Game means there are rules. Of course, there are situations in which you can't easily apply those rules, in which you have to apply GM Fiat(or make up a rule) to resolve a situation, but this is clearly not one of them.