This is the question.
Why is it non constructive?
I found the two answers very constructive and was evaluating both.
In a nutshell, it takes an opinion to answer that question. You're going to get a bunch of different answers in which you'd have to choose, some equally as good as others.
It is a shopping question.
Now, shopping questions are considered unsuitable for Stack Overflow (and generally the Stack Exchange network), for the reasons outlined in the blog I have linked.
The naming of the close reason is not as good as it can be - think of it more as "not suitable for this site" than "not constructive".