Each background is a handful of lego pieces. This is precisely how reallife cultures work: skills gained while participating in the traditions of specific groups in specific places.
That's a great way to describe how it works in real life; it's a
terrible model for a fantasy roleplaying game.
Everyone says they want "cultures" and "backgrounds" and (yes, even) "races" to be more flavorful and iconic, but then they backpedal and start talking about
individuals and
exceptions and
special circumstances and then they wonder why everything keeps coming out the same dull, flavorless shade of beige. They're homogeneous
because you keep homogenizing them; if you want things to be
special and
different, you actually have to be willing to let them
stay special and different. You have to be willing to say that they're not the same thing, that they're not interchangeable, and that they're not something to be ignored and that they're not
'guidelines' to be reskinned whenever someone says they want to play "a dwarf, but
not like all the other dwarves".
It is literally the same people complaining that "fantasy races" are just different rubber forehead aliens that refuse to let them be anything else. When everyone, every single instance of something is
'an exception to the rules', nothing is special-- everything is blandly, identically unique, just like everything else, and it's
boring. When you mix everything in the kitchen sink together, the only flavor you're left with is dishwater.