Agree Bear, i think that is how sport used to be like. Clubs would cross promote other sports, and there was a sense of community spirit between various codes.
Now, they purely compete against each other. They try to crush the opposition and reduce them to a forgotten sport.
Sponsors and media are largely to blame.
As a comparison, in the US, most big cities have the 'Big 4' teams - NBA, MLB, NFL, NHL - and they all seem to exist perfectly well with each other and all make millions of dollars and have saturated exposure. (Huge populations and billionaire owners help of course) a similar thing on a smaller scale can work here too.