Wouldn’t it be better if we didn’t tell them as there would be no chance of condemnation.
Well, you see, that’s where you’re wrong.
Someone used cancer earlier. It’s like having the cure to cancer, and keeping it to yourself. You have the cure, and sure, some people survive cancer without it, but still, many would do better with it.
Why would you ever want to keep the joy of Christ to yourself alone? The Gospel is not a twisted version of Christ’s meritorious work on the Cross, but the entirety of Christ’s story.
What the passage is saying is not that those who are ignorant will escape condemnation, but that it doesn’t de facto make them condemned. They can possibly still be saved by accepting Christ in a way without knowing it. You can see this in early works, that those who take up proper reason are taking up of the Word, the Logos, and so for instance it was assumed ie Plato would have been saved (though he died before Christ was born).
As Christ says, from those with much much is to be expected. From those with less, less.
It would be more an exception, in spite of their ignorance, not because of it.