These companies ultimately have the final say when it comes to the final product, and sometimes, the end result is not pretty. Every aspect of gaming falls upon publishers, and they hold many responsibilities during a game's promotion, release, etc.
While good practices help extend the life of a game, bad ones chop them up and sell them for money after all the components of a game finishes development.
(Or Early Access) While playing games in the middle of development sounds good on paper, paying for them is ultimately a gamble; there is no guarantee that they will be finished or represent the final product.
Sure, now you won't have all those discs cluttering your shelves, but what happens when the server goes offline? You won't be able to play them and if they're shut down forever, there would be no way to play those games ever again.