Turning off huts and events is a popular option (can be changed in the custom game setup menu). I think the main reason for this is that it makes comparisons between different players approaches easier, by reducing randomness. Also, there a lot of negative random events that seem pretty arbitrary and can be annoying.
On higher levels, AIs start with 2 scouts (I believe this is true of Immortal and above but somebody correct me if I'm wrong). As such, they tend to scoop up most of the huts before you can get to them, giving the AI a potential advantage above the ones they get from the difficulty level.
Turning barbs off is just a way of making the early game way easier. You can do it if you want, but I don't think anyone would take seriously an excited post about how you have stepped up your game by turning off barbs.
Giving barbs archery in the worldbuilder is just something you see in some of the games posted on the forums where people play at varying difficulty. Like if you want to play a Noble's Club game on Immortal difficulty, you can, but you will need to manually add archery so the barbs start with archers in their cities instead of just warriors.