if you look into the details ticket sales as well as concessions are a very minor source of income compared to TV deals.

With social distancing they will probably start making more money on TV deals which is their major source of income.
And thats where the problem comes in. What you are proposing is in direct competition with where they make their major income.

now this is for the NFL for example. Of course other sports are different and that is also why other sports already have these things in place.
I know figure skating has it in place. My daughter has a subscription for it. Soccer also has things like this in place for years.