Why shouldn’t we care about layer 2? You can do really fun and interesting things at the MAC layer.

You can do what you do at the MAC layer without any regard for whether or not it is "OSI layer 2", or whether your MAC layer "cheats" and has features that extend into layers 1, or 3, or any other layer. Failing to implement something useful because "that's not what OSI layer 2 is and this is data layer 2 and the OSI model says not to do that" is silly.

To stay on the main topic, same for the "normalization forms". Do what your database needs.

The concepts are just attractive nuisances. They are more likely to hurt someone than to help them.