Because it comes from gamers and people concerned about preservation of games. Why broaden it if the people who are pushing for the initiative don't care about other stuff?
Narrowly-crafted regulatory interventions are tools of the elite class to weaken the resolve and solidarity of the working class. That's my general reasoning.
I understand. If you don't care about this petition, you don't need to sign it. If you care, the amount of time and effort it takes to sign it is very small.