Further detecting an edit is easier...but adds a lot of overhead.
Basically for any value that is somewhat important and might need protection? Watchdog variable, which would very quickly consume a lot more memory and worsen performance as now every update to a variable also needs to update the watchdog variables.
And then you need to add some form of protection to the watchdog variables to prevent tampering with those...after all if someone updates both the watchdog variable and the normal variable at the same time? It looks legit. And sure there are ways to protect those...but it just adds more overhead.