I’d drop the word “open” here since some are closed, single-user, or non-federated whilst others aim for growth over all.
Another way to put “avoid a ‘one size fits all’ approach” is that the fediverse and those on it seek diversity in all dimensions (software, communities, connections, content-types, moderation strategies). This I see as the key strength of the fediverse.
I would communicate with the non-specialists by addressing the problems they have. For me, Twitter/FB shouldn’t be arbiters of truth and banners of accounts. They should provide more tools to place moderation in the hands of users. My dream here is a web of trust and it’s much closer to happening on the fedi than on centralized social media.