I believe when the Page/Site was set up Lynn set all members up to be subscribed to all of the forums which they could opt out of if they were not interested in certain forums.
I also believe that the forums are the only place on the site that has alerts available.
The rest of the site such as events requires the user to check in on occasion to see what is happening with the club. This includes but is not limited to club (Sponsored) events such as Meetings, Breakfast/Lunch meetups, Special Events, etc.
Events only requires a check in once a month or so to see what is going on weeks or months out and is usually major and regularly scheduled events like meetings, Breakfasts, and events such as club picnics, etc.
The forum is where weekly (Pop Up) events are posted such as group rides, Sunday Funday, etc. That are not planned well in advance due to weather, etc.
This allows anyone who wants to coordinate/lead a ride to post a day or week ahead and lead a meetup and ride.
I use this all the time to post my rides spur of the moment because of other commitments or weather watching.