Learn English – “To answer” versus “for answering”

gerundsword-choice

Between these sentences, which one is correct/preferable?

Answers are for answering the question, not commenting.

Answers are to answer the question, not to comment it.

Is "for [gerund]" acceptable in some cases, for example in set phrases?

They are both all right, but I would rephrase them a little to make them sound a little better, like so:

Answers are for answering the question, not commenting on it.

Answers are meant to answer the question, not to comment on it.

The first one, I think, is preferable over the second one. "for [gerund]" is perfectly acceptable in this case.