This doesn't solve it either, however. As an example, if I'm friends with 5 people who each have this setup, I'll have to pay to belong to each of their 5 separ

This doesn't solve it either, however. As an example, if I'm friends with 5 people who each have this setup, I'll have to pay to belong to each of their 5 separate shared Slack channels. And they would need to do the same for each of THEIR friends.