Nope! The main thing going for a distributed ledger would be global consistency, but there are some very negative downsides. It's slow, scales poorly, puts a massive burden on admins operating instances, and the blocks would be effectively immutable...meaning that if the contents of each activity were fully nested inside of a block, edits or deletions would be impossible. We already see problems with CSAM showing up in various blockchains, and a Fediverse blockchain used for social purposes would be no different.
It's just not the right tool for the job when it comes to social networks. There were a few early experiments in this area, such as Twister, which tried to build a Twitter clone on top of a blockchain using DHT. It has a huge list of limitations, though, and development stopped around 2020.