The Torah does not describe imposed observance on a mass scale. It describes maintained observance by on rare occasions enforcing Religious law. When the Sanhedrin starting executing too many people, because the Torah was not being kept, they didn’t ratchet up the enforcement, they quit.
It just won’t work against a large segment of the population.
So the argument is that it won’t work. If it doesn’t work, then presumably they’ll stop doing it.
But you of course agree that it is proper to force torah observance even on a mass scale.
Also, we have more resources than they had then. Chizkiya sent agents to search people’s houses for avoda zara, but they would worship after the agents left. But today, you can just bug the houses.