Not to be stupid here, but what exactly the heck is notes and why is it not part of the blockchain? I'm trying to grok the ecosystem a bit better here.
What would be their reason for running a blockchain fork which to my mind would be a hostile action.
Scalability. By having multiple blockchains which we collectively own a piece of the DPoS community scan scale. What doesn't necessarily remain the same is the percentages of holdings but that's not so important to everyone.
The social consensus is that 10% would go to AGS and PTS. As a result the community owns a stake in Bitshares Music even though it is a separate chain. Additionally Bitshares can communicate with Bitshares Music through ACCT (atomic cross chain transactions).
Notes had a separate crowdsale and you're free to buy some Notes if you want but it's not the same purpose of Bitshares. It's for music artists exclusively. In the future there might be a Bitshares VIDEO, who knows?