From the BIP300 Abstract:

> In Bip300, txns are not signed via cryptographic key. Instead, they are "signed" by hashpower, over time. Like a big multisig, 13150-of-26300, where each block is a new "signature".

In essence, block builders (pools) cast votes via special transactions on which sidechains to activate, deactivate and overwrite. They also vote on peg-out transactions (sidechain escrow withdrawal).

So as I understand it, miners will want to consider pools’ policies with respect to these questions when deciding where to point their hash. Not just the economics of income stream.

For example, one pool may support the activation of an NFT-focused sidechain, while another doesn’t. Miners will have to pick which pool they want to support.