Depending on the resource added and if you see anything while adding, it can be a gamebreaker. I love wonder-GP-farming, how about I add stone and marble to my fat cross right from the get go so I don't have to do what I usually do, which is to found cities in godforsaken places just to nab some marble or stone early on?
Or if you are a warmonger and give yourself copper?
Heck even giving yourself extra food makes it a lot easier to build workers and settlers early on.
If you give yourself Uranium or something, that's less of an impact since you can't see it from the start of the game. Not as gamebreaking but still a potentially big change, especially since you can't help but see what other resources are nearby as well, such as iron, and know where to expand to.
It is also fun to discover previously hidden resources when you discover, for instance, Iron Working. WB decreases that fun, perhaps more than it apparently increases fun, depending on the person--and aside from the "I wonder if I would have done as well if I played by the rules" feeling.
Anyway, what you are describing, and what the original comment described, is cheating. It is certainly possible to have fun while cheating, and yes, the ultimate point of a game is to have fun, cheating or no cheating. This goes for regenerating maps, reloading, or whatever floats your boat. Civ IV begs to be modded, and heck yes you can have fun with mods as well. As long as you don't cheat in multiplayer games, and you have fun despite your cheating, no harm no foul. Good luck have fun.