In Vanguard, weapon mounting has become more powerful than before. Due to the apparent benefits of abusing Weapon Mounting in Call of Duty: Modern Warfare (2019). It's like the developers heard what players complained about in Modern Warfare (2019) and decided to make it more overpowered (OP).
Damon 'Karma' Barlow decided to demonstrate just how broken this mechanic is and how bad it has gotten in Vanguard. Previously, players had to stay in their mounted position, but now they can move from left to right. While mounting is realistic, it makes things like camping a huge issue.
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Weapon Mounting in Vanguard
When a player uses a mountable position in Vanguard, they lose most of their recoil, the weapon stays perfectly still during aiming, and they just have to sit there. There is nothing more unfair than to players who are mobile and trying to keep the competition heavy to be shot just because they happened to enter a camper's crosshairs.
In the clip, Karma just needs to sit there and shoot anyone who walks by. Recoil doesn't seem to affect his aim at all, and it doesn't even appear that he feels it. If necessary, he can move left to the right for a better shot.
In competitive play, this is unlikely to become a significant problem. For tournaments and other competitive arenas, Modern Warfare turned off the mounting mechanic. The removal from competitive play is likely to happen with Vanguard as well.
It's true that this kind of technique is used in the real world and has a similar effect, but it's not ideal for gaming. There are times when realism needs to be replaced with fun, and something as OP as weapon mounting is one of them. It will be interesting to see if it even makes it into the full game, as more people are already raising concerns about it.