Hmm. Well I've never played 5v5, nor have I ever played CoD on the PC. But you seem to be saying that almost every map has a favoring towards a weapon class, which I don't disagree with. I thought the original claim was that nowadays almost all maps in CoD are SMG dominant, which isn't true. I will agree that almost every competitive map in Ghosts is SMG dominant, but that wasn't the truth in the last game and I don't think it will be that way in the next game. Even in Ghosts there are maps like Octane Domination where you could run 4 AR's and dominate, depending on the situation.

There are definitely advantages for different classes on different maps, and different gametypes for that matter. If what you're looking for is equality of all weapon classes on every map and every gametype, that's impossible. First of all, snipers will never find a competitive advantage on Domination. Never. Shotguns can sometimes be viable on certain maps on Domination and SnD, but not CTF. Pretty much anything on any map of SnD is viable in certain situations.

This is why you don't set certain positions specifically per player. You can't really have a "sniper" on a competitive CoD team, because they couldn't do anything on the respawn gamemodes. You can have an "AR" player, but that doesn't mean they must or even should run an AR on every map/gamemode. It's better to look at what the player is doing, rather than what they're using to define a "position". These positions change in every game, because sometimes they are needed and sometimes they're not. Like in Blops 2, for instance, there was a Support player(usually running an AR to watch over the OBJ and Slayer), an Objective player(usually running SMG, in order to move fast from objective points like hardpoint hills or flags on CTF), Anchor player(Can run basically any weapon, but most often AR. Their responsibility is to hold the good spawns and make the enemy team get bad spawns so they can stay close to the objective.), and a Slayer(fairly self-explanatory. They rotate around the objective points and kill everything to make it easier for the OBJ to do his job.). In Ghosts the positions are a bit different. There's 2 Slayers, an OBJ, and a Support/Slayer. Since there's a 5 second respawn timer and due to the map size and variability, there is no need for an anchor. It's more important to get 4 people on the other team dead, so you have 5 free seconds to do what you can with the objectives.