Well on Cod4 when you get deep impact and stopping power, nothing can stop you blasting through all of the walls on the map and killing people. The game should be equal, whether you've played it for years, or it is your first day. You should be able to get all the weapons and not have to battle people with Juggernaut and struggle to kill them until you can get it yourself. Trust me, Cod4 without perks is a whole different game, and a better one at that.
If you're saying the perks don't make a difference to the game then you are either too bad to notice or you don't pay attention to what you are doing. Rank means jack all the rank does is enable you to get more weapons and perks, perks are un-realistic to an intense degree and it ruins the game completely. Public gaming is for people who don't pay attention, but the game is better without perks and they should have made the game without them. Like Cod1 and Cod2 you just chose your weapon and you went.