During the private beta stage part of the process is to discuss questions that may or may not belong on the site. In addition the relaxed reputation requirements allow all users to vote to close a question as being "off-topic". Knowing this should all possible off-topic questions be discussed on the meta site or should users just vote to close the question?
Discussing all questions on the meta site will probably lead to a lot of noise in meta. This may be beneficial though as it records historical decisions about on/off topic.
Voting to close doesn't allow you to specify why (you can comment) and the question may just sit idle in the site. This doesn't help guiding the direction as the site as people may see that this type of question is allowed.