yes, that works - up to a point. Because sometimes people actively want to get into a conversation with people that are completely unknown to them, but only connected through a shared interest in something. Think striking up a conversation with a stranger in a bar, or while standing in queue somewhere.
This board for example: The only connection I have to basically everyone here, is that they are here too. Thankfully, all’y’all are nice people, but what would my options be if you weren’t? I’d probably have to count on the hosts here to make things friendly.
Generally, we need to recognize that there are different scopes of communication, different spaces with different needs and constraints. As soon as an internet space is open in the sense of “everyone can register and participate”, you are essentially dealing with the potential global public.
All it needs is a well-worded link in a high-traffic place directing new people to any given space to fill it up with a new audience - which might be friendly or hostile, come with its own agenda, might have an interest and understanding of the place, or just wants to complain… Any new social platform should keep this possibility in mind.