Change is always difficult.
So yes, having the right arguments is important. In a community for self-help privacy is especially important. Meta (facebook) has already proven many times that it cares nothing for users' privacy. WhatsApp is now part of that same company.
Hosting your community on open source software like Flarum allows you to:
- host it anywhere and thus own the data and give users ownership of their data
- review what the software exactly does
- customize the community with features that support its goals
- stay online, no restrictions or removal when content of your community is deemed unwanted
- moderate your content according to your terms
There's probably more to say, these are just a few thoughts.