For me the disadvantage is that you don't own it (despite that I strongly dislike that we're expected to rent everything from music, movies and software today), so when they for unknown reasons remove releases from their catalog, you'll have nothing!
If you take a look at movies and streaming, they are licensing it to be on a streaming service for specific time-period, I don't know if that is the case with music yet, but it could easily change to that in the future.
But despite all that (when it comes to music) I hate that they really don't pay the artists nowhere near an acceptable amount for the plays.
And here we are at the point where I'm not sure if it's good business to pay them the necessary amount, and if that's the case,- they (too) will cease to exist, if they change the level of the payments to substantially higher (again leaving you with nothing)!