I'm sorry but this is some dystopian bullshit that's all centred on the false premise that communities are anything other than the people who choose to count themselves among them and engage in them.
Reddit is just the tool some communities chose to use to gather their members and communicate. That's it. If a community decides that Reddit is no longer the appropriate tool for the job, they can leave and build their community elsewhere. That may be a bit of an oversimplification, given the resources and tools those communities might lose through the transition, but strictly speaking, Reddit can't do anything to stop the members of any particular subreddit going elsewhere, and a cryptocurrency absolutely is not going to fucking facilitate the ownership or mobility of a community.
It's a bullshit form of control that they want their users to willingly bind themselves to. Suddenly you're not just participating in a community, but you're genuinely invested, tied to something with a perceived monetary value, that even if you can theoretically remove from Reddit and take elsewhere, won't have any more value than people choose to place on it, and won't represent the community that generated it in any meaningful way.
It's literally "Hey, the more you use Reddit, the more of our crypto you'll earn, which could be worth more than zero one day! You better keep using Reddit, huh? You wouldn't want to lose that potential for more than zero eh? In fact, why don't you encourage more people to use Reddit too? Then they'll generate their own crypto, and the more people use our crypto, the more it'll be worth for everyone! See, if you get five more people to use Reddit, and those five people also get another five people each to use it etc etc etc..."