In modern chess, engines have gotten good enough that we generally do know the top moves and humans can't beat them. We can even numerically assess someone's chess play with a computer, which we call "accuracy". Obviously they can always be improved further, and there are a handful of situations where they might misevaluate, but it's still pretty incredible.

Engines have only made chess more exciting as they have shattered a lot of old theory and helped people find a lot of new and innovative ideas. They are an incredible aid in analysis and tournament prep.