From what I've seen I would basically chalk it up to the following:
A good advice question is one that experts are likely to have an opinion on.
While this is tricky and can result in a larger than average number of answers, I think with a very reasonable amount of community moderation the potential issues are fairly negligible considering the potential benefit to users.
I think we need to recognize that even straightforward questions that we all find appropriate for SE occasionally produce a range of creative and distinct "correct" answers. In these circumstances we don't turn back on the question and decide it must not have been specific enough, we vote for the ones we find most appropriate and go from there.
The very fact that Software Recommendations SE exists seems to me to be proof that questions with an array of potential answers are entirely compatible with the SE format.
Ultimately, I think the priority should be sharing knowledge and experience. There are obviously some questions that are too broad to attempt to address in a single answer and those will be closed as such. But the community having a range of opinions about a given topic is, if nothing else, proof that the topic is worth the consideration the asker is putting forward. And by voting we can quantify that worth.