“Driving too fast for conditions” won’t be enforced by cameras, will still exist if the road is modified and is 100% subjective which is a problem speed cameras don’t have so you should be happy about that.
It might be more effective, it’s still not possible to change all roads as quickly as speed cameras can be deployed.
It’s also a very stupid argument, that’s like saying “If that person didn’t want me to steal from them they shouldn’t have left their car unlocked.” The rule is there, it’s your responsibility to respect it no matter what the road looks like. Both things need to be used in conjunction, roads need to be adapted to their limit but you need something to enforce the limits too.