Broadcast territories aren't arbitrary. They're geographic.
Sure, you are correct that there is a 'geographic component' to blackout rules/broadcast territories. To say that these blackout anything but absurd, however, is absurd.
That doesn't mean the rules are "absurd".
Eastern Montana blacked out from SEA games - absurd;
Tulsa, Oklahoma and Little Rock, Arkansas being blacked out from HOU (and TEX / STL / KCR) games - absurd;
Northeastern New Mexico being blacked out from HOU (and TEX / ARI / COL) games - absurd;
Las Vegas being blackout out from ANA, ARI, LAD, OAK, SDP, and STG games - absurd;
Des Moines, Iowa being blacked out from CHC, CHW, KCR, MIL, MIN, and STL games - absurd;
Hawaii being blacked out from OAK, ANA, LAD, SFG, SDP, and SEA - absurd; and,
the absurdity is not limited to the areas noted above...And like Craig noted, fans in many of these markets are blacked out despite the fact that numerous teams do not even broadcast in those makets. Take Hawaii for example - blacked out from 6 major league teams despite the fact they are thousands of miles away (and there is that whole pesky Pacific Ocean thingie between 'em to boot) from any of them with 2 teams not being broadcast on any of the islands (SEA and SDP) and 2 others (SFG and OAK) are not primarily available either.
Absurd.