As someone that has used ad blockers for just about as long as I have been able to, I would like to think that this is true. However, I’m not entirely sure that it is. I’ve heard that a surprising percentage of people just don’t even know that ad blockers exist. If that’s the case then they may be very well aware of what is happening. (Using made up numbers for the sake of argument since I don’t have real numbers) Like if only 5% of users use ad blockers and doubling the number of ads they show only brings that to 10% then it is certainly worth it financially. I doubt that if you were to graph that curve it would be linear - there is certainly a point where you inundate users with so many ads that even non-technical people will start learning about ad blockers. Regardless of what the real numbers are, I would be very surprised if they are making decisions this big without at least being aware of what those numbers might be. And if they can make a small amount of money indefinitely but they have evidence to suggest that they can make even more money also indefinitely then the financial motivation is obvious. Not all infinities are the same size.
Even within those services you could also just have an actual library that functions the same way as an iPod. You can create playlists or just play your entire library if that’s what you want. There is no need to interact with any algorithm in order to use these services.