I imagine that they would. Text is trivially easy to store, and storing multiple versions would let them catch users who might edit away rule breaking they posted to avoid bans, but it's probably one of those internal tools.

From a data handling perspective, it'd be more efficient to handle edits by having a common id field, and an additional version/edit counter that increments --adding the edit like its a normal post-- , than it would be to edit data the usual way, since you don't have to go back over the whole database to find the comment, or worry about it falling out of sync if one copy of the database has the edit, and the other has the original.

You'd just need to fetch the comment by id, and the database entry with the highest version count to display it, which would be fairly easy to do.