A thousand people create alternative NBA subs and discussion boards every day. How will everyone know which exact one of them to go to?
If you think the solution to blocking a sub (or all of Reddit) is "a hundred million people can just all decide to go somewhere else the next day", you fundamentally misunderstand how the community and network effect works.
I mean, it's really not at all that difficult to search for subs on Reddit and see how active they are, and then subscribe accordingly and join in on the convo. Who cares if everyone goes to the exact same one? If people spread out to a few active subs, then the discussions will continue there. A few million here, a few million there.
Some of that hundred million would disappear, sure, but hey - what percentage of subscribers are relatively inactive anyway?
If you think the solution to blocking a sub (or all of Reddit) is "a hundred million people can just all decide to go somewhere else the next day", you fundamentally misunderstand how the community and network effect works.