This isn't the case, most networks are extremely technically sophisticated (ESPN especially) the misunderstanding here is business related. TNT and ESPN make millions (in ESPN's case billions) a year in subscriber fees from cable operators. ESPN alone makes $3-5 from each cable subscriber in the US (there's about 120M of them) each month. A significant portion of these network's revenues are made on subscriber fees. The solution you propose jeopardizes these agreements for what would currently be a paltry amount of streaming ad revenues.
If they want to cut out two middlemen (the network and the local cable provider) then the NBA must learn to create a steady audience and get money from advertisers, which is a different skill than putting on ball games.
Seems like a fairly straightforward solution to me. My assumption is that the powers that be aren't technologically sophisticated enough to understand the benefits of it.