Every since the first Infeciton came out, the biggest issue of the game is survivors camping in a corner of the map where they have full view of everything infront of them with no way of getting behind them. This is even more so in Black Ops 4. Before the game mode is ever added back as a featured game mode. Change how the game works for survivors. Make it so that the survivors can not stay in one area for a certain amount of time so that they have to be constantly be running around. If they try to stay in one place for too long, they start taking damage until they move. Don't instantly infect them because that would be unfair, but it's unfair when all but three people sit in a corner where everyone has a spot they can watch and so no zombies can even think of getting close. Yes, we do have combat axes but not eveyone is good with them and they can be inconistant with how you throw them.
Thats the strategy with infection. It was in WW2 and will be here. That being said, I have played in only a handful of these games but usually the infected win dont they? They did give them the combat axe.