That's actually myth. Widely believed, but not actually true.
The aluminum wires of today are a different allow of that simply does not have the problem anymore. It's a solved issue. You don't even need anti-ox on the connection.
Building code is not a standard by which to judge possible practices, it just formalizes the normal approach to prevent halfassery. (And arguably, to prevent disruption of established businesses in a regulatory capture kinda way.)
The aluminum wires of today are a different allow of that simply does not have the problem anymore. It's a solved issue. You don't even need anti-ox on the connection.