Once again, I would encourage everyone who is saying "just play tactical" and it's easy to deal with campers to watch this:
The game has a multitude of issues contributing to the problem. Half the battle is just crossing an open street or area to get to a building or area where they are, and most people's response to that is use smoke grenades, which okay sure that's fair, but you can only have tactical grenade. So then you don't have the apparently infinite stun/flash/gas grenades you think we have to deal with the actual camper in the building. Which also disregards the fact that a lot of buildings and power positions are large enough that you can't reliably grenade or flash them, and pushing on them in either scenario often runs you into the two claymores they have up because they always have two and they're recharging because they're running Restock because if you're camping there's not much reason to NOT run that.
So yes, calling out people for expecting to be able to hipfire MP7s nonstop around corners and win every time is totally fair. But when a very large portion of the community who have days/weeks/months of gametime in each of the the past decade of CoD games are all calling out the exact same issues, maybe you need to acknowledge it's a thing? And even if it wasn't, people being unhappy about a big gameplay shift that was NOT made apparent pre-launch from the last 10 years of CoD games is also fair.
Like, imagine calling out people who are unhappy about Yakuza 7 having a totally different core gameplay system by saying they just need to adapt and get good. If you think the new style is great, that's fantastic, but being super defensive about people who are unhappy about an unadvertised big shift from the last 7+ entries is a bad look.