Basically, some developers don’t believe a subscription can work for them on its own. Unless they’re getting paid upfront to cover the cost of their game. It also may lead to the bigger developers getting most of the cut and the little guys getting less. Which would not be beneficial to the smaller companies.
Just look at it this way, EA, Rockstar, Sony, Activision, Ubisoft, etc know that putting their games in someone else’s service at launch or their own service, is not going to cover the cost of big games. Not without a large amount of subscribers or a huge check. Or you would be seeing them do that now. These companies sell their games first. Then, when they made what they are going to make on their products from the sale, micro transactions, dlc, etc. Then you will see them possibly put their games in a service to make more profits on an old game.
Clear examples are Sony putting games in PS Now or Plus AFTER those games have sold at retail and digital. EA doesn’t put their new games in Origin and Access until AFTER their games have sold. Capcom and Rockstar didn’t do it until after their games sold then took a big paycheck for more profits. Only one company is doing theirs at launch. Which is to increase the amount of subscribers. But without numbers to verify, we have to go on their WORD that it’s successful. But as we have seen, their games at retail have sold less. Only their WORD that they have sold more. We know gamers played more. But no numbers they sold more.
I look at it this way, if I had a restaurant with a buffet for a dollar,and I’m serving expensive gourmet dishes alongside burgers and tacos, I will get lots of customers to come in to eat. But would I have enough customers to cover the expensive dishes?