There’ve been several discussions on meta about using Discourse as a social media platform (see, for example, Using Discourse as a social media platform). If the Clubs (that’s how Invision calls them) are essential to your project/platform, I’d personally say Discourse is not the best option for you. Why try and stretch a platform designed for asynchronous discussions into something that’s inherently different?
Also, let me ask you a different question. You propose a set of users might create a group, self-manage membership, network & organize events. Where’s your input in all of this? Why would those users use your website, and not create a Messenger/WhatsApp/Telegram Group? If you want people to coordinate offline events, you want real-time communication. Messengers (in general) allow you to call people, send real-time push notifications (not an easy option for self-hosted Discourse instances), and most importantly you don’t have to check a separate app. If your target audience uses, say, Messenger to keep in touch with friends, they’ll see any updates in the “Gardeners Group” even if they do not intend to check if that group has new messages.
Whereas if you handle this via a separate platform, your users have to open a separate website (or app) to get updates. While this may not sound like a big obstacle (it’s not hard to open a website), it actually is: people are extremely reluctant to add a new app to their routine if they can avoid it.
Not trying to discourage you from pursuing your ideas, just wanted to make sure you thought about such issues before you make platform decisions.
While this is true, it’s only practical if it’s an official plugin: i.e. there’s a team of engineers who are paid to ensure it’s compatible with newer releases of Discourse. Otherwise, you’re either locked in to a specific Discourse version or you have to constantly hire someone to update the plugin.
actually I’m surprised no one has said this before: Discourse can be $0/month and Invision starts $89/month. For some people that’s already a definitive argument in favor of Discourse.