"Messaging" and "messaging system" is too nebulous.
Why are you not using a mail server?
I'm totally serious. Been there, done that (used qmail as a message bus). It works great for certain types of requirements.
Sometimes you badly need persistence. Sometimes it doesn't matter. Sometimes you need massive scalability. Sometimes you need reporting. Sometimes you need to be able to provide a dashboard to visualize pending messages. Sometimes you need to be able to publish to large numbers of listeners at once. Sometimes a small number of listeners needs to aggregate events from thousands or millions of sources. Sometimes you need a message to only be processed exactly once.
Often you can nail down some of those issues from the outset. As well as scale. But often you won't know in advance.
More importantly: Your system will almost certainly use a database server. Unless you have clear indications that your needs can't be met by the database server, adding a "messaging system" is one more dependency which you don't yet know whether or not you'll actually need. One more thing that can fail.
If that's the right tool for the job, then I wouldn't argue with you. But my messaging needs are typically solved by tools like WebSphere MQ, RabbitMQ, etc.
Why are you not using a mail server?
I'm totally serious. Been there, done that (used qmail as a message bus). It works great for certain types of requirements.
Sometimes you badly need persistence. Sometimes it doesn't matter. Sometimes you need massive scalability. Sometimes you need reporting. Sometimes you need to be able to provide a dashboard to visualize pending messages. Sometimes you need to be able to publish to large numbers of listeners at once. Sometimes a small number of listeners needs to aggregate events from thousands or millions of sources. Sometimes you need a message to only be processed exactly once.
Often you can nail down some of those issues from the outset. As well as scale. But often you won't know in advance.
More importantly: Your system will almost certainly use a database server. Unless you have clear indications that your needs can't be met by the database server, adding a "messaging system" is one more dependency which you don't yet know whether or not you'll actually need. One more thing that can fail.