If you come up to me and say 'well I want to play a Barbarian, what Barbarians are there?' and I say 'I don't know, you tell me what Barbarian tribes are around, or where your Barbarian came from' then that's the player's cue to go make up a cool Barbarian tribe. And if his friend is a druid, then that interaction could be made easily. But I don't need to get involved, I don't need to sketch out backgrounds for every single class and race on the offchance a player might take one, which is a hell of a lot of wasted work (why sketch out four cool origins for a Dragonborn character if... no one makes a Dragonborn? Wasted effort ho).
There is nothing wrong with our approach for some people. However, "You guys come up with it and I will make it work" is not something I want out of a fantasy rpg. I don't want it as a GM or as a player. As a player, I want to see your DM vision of the setting- not some random hodge podge of whatever people bring to the table. If you have not done the general overview, I can't make any knowledgable decisions about the setting and it kills my immersion from the start. If you can't be bothered to create the setting (or use a published one), I can't be bothered to participate. I will find another group or run my own game.