A question like that isn't generally off-topic, it's just a bad question.

If the author already decided what the solution to their problem must be, than they exclude possible better solutions. Questions like that are also known as [XY problem questions](http://meta.stackexchange.com/questions/66377/what-is-the-xy-problem).

The author should be made aware of what they're doing wrong and should be encouraged to edit their question. If they refuse to do that, a downvote is in order.