Maybe, in spite of all the time I've been on this page, I don't really understand how "Answers" is supposed to work; but I've always thought that if a question was still open it meant "feel free to answer". :) I've just always figured that sometimes whoever posts the question gets whatever he/she wants and selects "best answer" before moving on. In the meantime, HP leaves up the questions So, yes. If I think I have a half-decent answer to contribute I'll answer.
Most of the time I come to the Answers section first to look for ideas for Hubs (and there aren't many these days with the kinds of questions so many people post). If I don't see an idea for a Hub I may just leave. If I'm bored and looking for something to do that doesn't take bothering thinking up a whole Hub then I'll answer a question (again, if I think I have something to contribute). I keep copies of my answers (just what I write - not any part of anything anyone else wrote with the question) in case I decide to, say, post my answers on a zillion of my own blogs. (lol)
Then, too, no matter how long I've been on this site, I don't even really know how to do "write a Hub about it" without being uncertain that the Hub is even "connected" to the question (particularly after creating a decent-quality title out of something like a poorly written or presented question).
Nobody asked, but I really think the whole "Answers" thing could use some changes. It's too bad there isn't a feature for a person to "write a Hub about it" without having to worry about a whole, big, complicated, thing of coming up with a "mini-Hub" BUT being the one who gets "credit"/potential earnings for an substantial answer to a question that requires more a very few words/lines.
In any case, I just kind of figure that if people weren't supposed to answer once a "best answer" has been selected, the option to answer wouldn't still be there (for, for example, the bored among us :) ).