There is no such thing as a team having too many good players.
Obviously if there's a top tier player available that you can pick up with the pick, that's another thing entirely and you would be foolish to reject someone like Jokic (to pick an extreme example) just because you think you have a 14% shot at Wemby, but generally speaking that's not because you're too loaded on talent, it's just choosing someone who is established over a future prospect.