Kabir Honestly, most CMS already work that way. You can set up a sales store with Wordpress, but you need to do it using a plugin. SEO? For that too, you need a plugin.
In fact, the Gutenberg feature that Wordpress introduced hasn’t attracted much interest for years. As someone who has been using Wordpress for over 10 years, I’m sure I will never use the Gutenberg editor.
Returning to our topic, as you mentioned, Flarum already has extensions for all of these. Moreover, most of them are developed by the FoF team, so there’s no risk of the development being abandoned one day.
Besides, I have witnessed dozens of times that when some extension developers abandoned their projects, other developers continued them. I have even taken on the maintenance of at least two abandoned extensions from different developers.
So, I find it hard to understand what problem you are experiencing. MyBB is completely dead. Other forum software is similar to this—even the paid ones.
Forums have evolved nowadays. Instead of forums that cater to everyone, it’s necessary to set up small forums that focus on a specific topic. This brings about many different needs. Why would I want features in my forum that I will never use?