But when something is a decentralized immutable ledger and global consensus, it tends to solve problems of decentralized immutable ledgers and global consensus.
They are the structure of of decentralized systems. A comment system can be seen as (and is possibly already implemented as) an immutable ledger of transactions - adding comments, voting, edits etc.
So decentralizing those things that can be represented at their core as a ledger of transactions is very much a problem which blockchains solve.
