Onii-chan
King
Well it's not that scouts aren't good, it's just that there are so many other things you want to build in the early game as well. I normally wouldn't build more than 2 (maybe 3 on a huge map)
4. They are super useful for herding other countries' units so they don't get in your way. Most importantly, you can stop a pesky foreign settler from encroaching. (Without declaring war). It takes some maneuvering, and you have to put the scouts a few deep, but it can work. BTW, foreign settlers can move THROUGH your units, so plan accordingly.
missionaries are the best scouts in the game
Nothing is more valuable early game than being the first to meet a city state and the AI will never kill you with his 4 warriors...
Don't send your slingers too far out? Just because people are comparing whether to build scouts or slingers early doesn't mean they have the same roles. Keep slingers at a short-to-medium distance from your capital, use them to maintain line of sight to prevent camp spawns, get the boost for Archery, then clear the area with your army. Yes, you might miss out on a couple tribal villages this way. You also won't die.And the final killer, how is that slinger getting back exactly? Oh yeah you can upgrade them to archer to stop an AI rush. But it'll be some 10-15 the turns before they get back and that's if barbarians don't kill them first.
The scout is worth the discovery bonuses, he gets bonuses better then slingers, so slingers are just crappy scouts.