Respectfully, who cares?

Hard truth… you’re not important. None of us are. No one cares enough about your opinions that they need you to “maximize your reach” by posting in multiple places. That is entirely a you problem, not an us problem.

No one is forcing you to post everything multiple times to multiple communities. You’re free to choose one and post to it. if it’s interesting enough, someone will likely share it to other communities. And if it isn’t interesting enough, they won’t. Simple as that.

that’s… how… it… works

Also, you talk as though browsing r/all on Reddit doesn’t also show multiple copies of the same post sent to multiple communities. Of course it does. Declaring something the “main” community isn’t going to change that anyway.