Personally it's the freedom that I enjoy more. For example I have 400 songs into my Christmas playlist. There's so many duplicate, like Have Yourself a Merry Little Christmas is there 9 times, but it's fun to have the different versions. Sure it would be fine to have 2-3 albums of Christmas, but then I would have to choose and there would be less diversity.

It's also amazing to discover stuff and follow new paths. Sure you could try to buy a random new album during a month, but that would be your whole exploration for that month, I could explore many more albums in a day. Right now I listen to a lot of a cappella group because of a good Pentatonix song I heard a few days ago.

I also enjoy just being able to listen to any CD. When I heard about A star is born, I was curious and I just had to open Google Music to listen to it, without paying more.

Would 12 CD a year would be enough to entertain myself? Yeah I have no doubt, but it wouldn't allow me to discover to having that much freedom.

For me it's much more than "I could buy CDs". A sub to Apple Music for example lets me go on musical journeys.

I listened to the many versions Vivaldi's 4 seasons the other day and enjoyed hearing how different orchestras performed. I have taken a dives into 80s rap/hip hop, or hair bands, or whatever else strikes me.

Those types of exploration were not possible in the days on only buying CDs.