But it stops you from getting an equivalent coke from any other vendor, even if you might want to (because it might be cheaper). You're assuming that everyone finds it as important as you do that your “Coke” comes from a specific manufacturer regardless of what the product actually is or contains.

For Coke you might be right about most people (though not me) but there are plenty of products where brand loyalty isn't a thing. People just want some decent hand tissues around, nobody cares if it's made by actual Kleenex.