Another benefit that others haven't mentioned, is that if active server behaviours are needed, you can attach a 'server' like a client. In some circumstances,

Another benefit that others haven't mentioned, is that if active server behaviours are needed, you can attach a 'server' like a client. In some circumstances, interacting with users via the database as a messaging system can protect them from issues with your server code, and server outages: if your server goes down, users will still be able to log in and interact with the database via client side code - they'll only lose access to server related functions.