The 3.0 firnware let other usb controllers work but it was pretty hit and miss ex. being the mayflash adapter worked but not the official adapter and the brown townog stick was digital and not all the inputs worked. Most likely it was only meant to make room for stuff like the pokken controller and they unintentional made generic usb controllers/adapters work in the process.
Now this feels intentional since it actually works woth the official adapter now and it works like a charm, brown townog support for the stick and everything works fine. Also good news for multiplayer stuff since now I don't need to waste money on extra pro controllers.