I've worked on an organic dairy farm that had its own pastuerising and bottling plant and sold direct to the public and through local shops.
As far as I could tell, they didn't make any more money per litre than they would have selling in bulk to the big creameries.
What it did do was allow them to have pasteurised milk, processing capability, staff and distribution to make and sell real added value products - cream, creme fraiche, clotted cream, butter, yoghurt, chocolate milk, chocolate sauce, etc. I think they barely managed to make that pay any better, either.
They did have the satisfaction of employing local people within that equation, and of seeing their own cows' milk being drunk and eaten locally - but it was a lot of hard work for them to keep that all running.
They don't do it now.