Techies, is this a viable way BHVR could stop hackers in real time?

Yes, and also no. It really is an arms race, there are some things they could do, but at that point its a matter of what parameters you allow.

For example, lets just look at one possibility, of a cheating survivor player's movement speed.

Scenario 1:

Survivor: Hey server, i can move at 200% movement speed permanently

Sever: Cool

Now they do a patch that makes it so the server will know that you can only move at 200% movement speed if you run background player and only for 5 seconds.

Scenario 2:

Survivor: Hey server, i can move at 103% movement speed permanently

Server: Cool

Now they do a patch to fix this. But 103% movement speed is possible with MFT with a condition.

So it creates this scenario where your detection is:

if survivor movement speed > 100% for some amount of seconds, but also when they don't have MFT and endurance, but also if they don't have this other perk:

then ban survivor for hacking

else they are good to go.

Now everytime they do an update to perks they have to go in and sift through that complicated logic to make sure they don't accidentally start banning people. Maybe create an new KILLER perk that makes survivors move faster as a penalty, but gives the killer some buff. Or maybe they create a new killer power that makes survivors move faster but gives some kind of debuff. So now the logic becomes super complicated.

The better solution is multiple things:

1. Better anti-cheat and banwaves. You always ban in waves, not immediately. Pirate software has a few clips where he explains this well: https://www.youtube.com/watch?v=2YUmMFwSXpU https://www.youtube.com/shorts/cADaFm__ApQ
2. A replay system, this would tie in with player reports, where when someone reports someone for cheating, a replay is created and can be played back by someone to view the match and determine if someone was cheating.
   1. If this system becomes too hard to manage for the devs because of too many reports, they can replace it with a system by which players can vote "tribunal" style, similar to overwatch in DotA where you can view replays, and vote whether someone should get banned.
   2. You could even go so far as tie this into AI and machine learning to take the match data and determine if the person cheated.
3. And finally compensation. If someone in a previous game was banned for cheating, you let the person know, and compensate them. Ranks don't really matter anymore in DBD but in say chess for example, they give you back your rating. In DBD, tossing you 100k bloodpoints would be enough for most people.

As Reinami mentioned, it becomes difficult to maintain server sided checks with every update. Additionally, every check you add is going to come at the expense of server resources. AWS isn't cheap, and they would likely have to scale up memory and CPU allocated to their VMs if they were to add more server sided checks.

Yeah server resources are also part of it for sure.