True. But that does not mean those rights were not valuable and crucial for the future of the sport. The big market teams cried foul and won the rights back for nothing. One can say they deserved it because they paid more for their big market team, but one could also see that if MLB controlled streaming rights they would actually have a shot at a solution to the big market/small market revenue disparity. The NFL and NBA (mostly) solution where much of revenue is pooled.
Just because they had done nothing with the rights does not mean they should have given them up for nothing.
BTW on your question about the Phillies, probably nothing is stopping them from creating their own streaming deal. The NBC sports networks are on more streaming services than anything else, so I am guessing the attrition in their revenue has been slower than other teams. Probably means NBC is accepting less per month than Bally did to stay on the services. Eventually the Phillies will have this problem too. There will need to be a regional solution also. One should get all 3 teams (Phillies, Sixers, Flyers) for $20-$30 a month. If it is that much per team viewership will crater.
If the 3 leagues got together and bundled all of them nationally I would probably subscribe. If it is sport by sport I think I am 75% likely to get baseball and maybe 25% likely to get any other sport (I'd just watch national telecasts in basketball and football).