Licensing of syndicated content. When an OTA station buys programming, they buy the right to air it in the specific geographical area that station is licensed to broadcast it, so the production firm can sell it in the next city as well.
If the station streams that programming online, there's no clear way to limit the broadcast to the same (or any) geographical area and that means the price would be a lot higher. Basically, the only content they could stream would be their own stuff, like news. And even then, TV production is a myriad of sub-contractors and small production firms and the contracting in place might only release the right to broadcast in the specific area (so, if they get a story of wider regional or national interest, they can license that content to other stations).
On the other hand, if the production firm streams it online (or licenses it to Netflix or to someone else with streaming rights), the content isn't exclusive and can't be relied on in the same way to drive eyeballs to the TV station that might license it, and the content would command a lower price - so the production firm is only interested in that if they can command a price from streaming that makes up for this.
It seems that production firms are increasingly finding that last possibility to be viable, and given the fast migration of viewers online, it's only going to go that way.
If the station streams that programming online, there's no clear way to limit the broadcast to the same (or any) geographical area and that means the price would be a lot higher. Basically, the only content they could stream would be their own stuff, like news. And even then, TV production is a myriad of sub-contractors and small production firms and the contracting in place might only release the right to broadcast in the specific area (so, if they get a story of wider regional or national interest, they can license that content to other stations).
On the other hand, if the production firm streams it online (or licenses it to Netflix or to someone else with streaming rights), the content isn't exclusive and can't be relied on in the same way to drive eyeballs to the TV station that might license it, and the content would command a lower price - so the production firm is only interested in that if they can command a price from streaming that makes up for this.
It seems that production firms are increasingly finding that last possibility to be viable, and given the fast migration of viewers online, it's only going to go that way.