Chances are the Mod who handles the ticket can't ban the user. Most Mods can only nuke Newbies. The post will get deleted, but the user won't get banned.
This may be true, although the mods aren't robots and can pass up on taking a action and leave it in the queue for someone who does have the capability of taking more serious actions against the account. For example, I've reported a few people in the past which I assume were left as I've received messages from cyrus telling me the accounts have been banned a few hours after the initial report.
Threads are able to include more information than you could on a report. The report field is quite limited and I often find myself having to recheck what I've written. Plus, I'm not sure how clear longer reports are for the moderators.