Caporegime
It's more based on wealth, the teams forming the super league are so wealthy it's difficult for them to be supplanted by lesser teams anyway. It's like ollies said about Bayern as soon as any of their competitors start to pose any kind of a threat they just swoop in and take their best players to keep them down.
This is another example of why its hard to be anything but cynical in this day and age. Bayern may be abstaining from the SL but is it because they believe in fair competition and how things run at the moment or is it because they don't like competition outside of the CL and they have a sweet thing going in the Bundasliga at the moment. They pluck players from their direct rivals all the time and have done for as long as I can remember so they don't care about fair competition. Like all clubs they are entirely in it for themselves.