Certain things they'll likely introduce with their tokens might not be possible on Lightning given that they are using a centralized chain. It looks like communities will be able to fork the "blockchain" and have their own tokenomics or whatever ... tokenomics/contracts/rules don't need to happen on a blockchain but a lot of these people in that space believe that they do, i.e. they like to LARP decentralization.
Moreover, Reddit communities will also have the ability to fork blockchains through community-based decisions, in addition to allowing the scope to explore new monetization strategies with Web 3.0.