I don't quite know what you mean by "monopolizing of fan bases"... Comcast paid the most for the Blazers' rights, and the Blazers took their money. Did Comcast make a good business decision to pay so much? It's not clear whether they did or not (we don't have access to their books).
Did the Blazers hurt their long-term bottom line in pursuit of more money in the short run? Perhaps. But in the long run we are all dead and I'm not sure that, of the fans the Blazers have lost in the last six years or whatever, the broadcast situation is as big of a deal as the extended mediocrity and terrible luck with injuries.
Ed O.