I just looked and Apple doesn't release numbers but its estimated they have over 40 mil subscribers. It was estimated around 25 in 2022. So yea they're doing very well and they do really well at awards time too.
that said, I can't imagine MLB drove out new subscribers all that much so I'd generally agree. Granted, I did it last game. Its $10, and you get a whole month so the game plus a month of binging their shows for $10 isn't bad at all. Especially when a burger at mcdonalds is like $13 now. But the nfl on the other hand when Amazon did it for the first time a few years ago it worked just how they wanted, a record spike in subscriptions because of it. usa is just nuts about the nfl, as someone who's blah on nfl it still blows my mind.