This is a good point, but many people seem to forget that most misdemeanor criminal offenses in the US are punishable by fine and/or up to 30+ days in jail. People do not often get the jail time so most don't even think about it, but it is available as an option to the judge for things like repeat offenders.
Which fraternity?
No, it is not, because background check and other third-party intelligence firms aren't purely reactive now, they have and use tools to proactively vacuum up public records and maintain their own DBs. After-the-fact sealing of arrest records or expunging of convictions has no effect on data that is already in third-party hands.