Well the original intent of allowing duopolies was to keep a failing station from going dark.
Now we run up with a couple of issues. TV needs some sort of regulation. One can argue free market is best, and it probably is but the issue with TV there are not enough allocations to allow a free market.
As you saw with airlines, when they were deregulated a bunch of start ups came in and quickly failed. Which is a good thing, as only by failing can you see what NOT to do.
Now with little regulation you have to main issues with TV. One is the fact if we allow free market, clearly we will have a limited number of stations groups control the TV sector. Which is bad. If we were to stop a duopolies or LMAs what would likely happen is we would see more shop at home 24 hour infomercial stations. As these make money.
It's a shame with digital coming the FCC doesn't redo the whole TV mess, with everything from maximizing allocations to creating regional higher power stations.
HDTV is good for sports and nature shows, but there is little else use for it. I mean are the Simpsons any MORE funny if the show looks clearer? Is Dateline anymore informative if we can see the pours on the guy's face?
This is where the FCC made their issue. They should have concentrated on Digital and since 1 analog station can equal 5 digital station, they should give analogs only one of those five channels and throw open the market.
Then you could have say the high VHFs for networks, and end having affiliates. Just have like ABC be channel 7 and broadcast on channel 7. Local stations would not need to be affilated and could go to UHF.
That is obviously not going to work because local stations would die, but hey they died often in the 50s and 60s, but eventually someone got the programming to be competitive.