Blackouts occur as a negotiation between local channels and the regional broadcasters (gate keepers), in general, such that local channels get priority over regional broadcasters.

Here is an example of a gatekeeper forcing blackouts the other way around [0]. The content producer was required to enforce a blackout on local channels as part of the deal with the gate keeper. Net result? Consumers lose.

[0] http://articles.philly.com/2014-03-27/news/48599544_1_philli...