I've used Community Builder on Joomla sites for nearly a decade. I built an education site and a church site using the system. However, those early builds took a lot of time to get right. Today, the system is easier to use (especially for you) and gets the job done. I know other community-type components exist, but since I use this one, I just want to describe the possibilities using the pro version along with Acymailing.
First, it's your opt-in form that creates users on your site. And you want users. If you want them to pay subscriptions, that's great, and Passive Ninja can handle that for you. However, even if you just want to make a website about recipes from the Civil War era, you'll want others to join your site. It makes them a part of the experience, but it also gives you the opportunity to communicate specifically with someone who wants you to send out relevant content. That's HUGE! You find a store that sells the right kind of shortening for the recipes and you send out an email (using Acymailing) telling others about it. Maybe you get a commission from the sales. Maybe YOU own the store.
Community Builder also lets you make as much info as you want to be required. If you are running a financial site and are giving away a free guide, you can ask for people signing up to fill in a form that tells you as much or as little as you need to know. Ask about net worth or retirement age. Get phone numbers. It's fully custom. You can get a name and email if that's all you want, or you can get a full profile.
Acymailing is nice because it integrates with CB and allows you to capitalize on the new list of interested people. It's legal, includes an opt-out message, and allows you to target your marketing for FREE and without importing and updating cumbersome mailing lists.
Community Builder can also be set up to allow users to subscribe to your site. Charge them $5 a year to learn your latest quilting techniques or $200 a year to follow your investing advice. Passive Ninja uses it to charge a yearly hosting fee. Make it a monthly membership club that sends out a box of chocolates. Constant revenue is nice, and it's what most of us are looking for, so contact Passive Ninja to see how you can achieve this goal.