The community here has closed a lot of questions that ask for music book recommendations, and there have been some discussions here on meta (here), where people say that most likely, those questions won't be accepted here.
But recently there a software recommendation question (here) which is on topic.
I can't see the difference between these two kind of questions. They both ask for lists and are bound to be primarily opinion based.
How can we allow the one kind and not the other?