> Why any of this was necessary instead of using the built-in Feeds and moderation capabilities on Bluesky is unclear.

Assuming you absolutely trust Bluesky-the-company to behave itself now and in the future, it probably isn't necessary. If you don't, then this sort of step towards real decentralisation is important.

This largely makes Bluesky-the-broader-network immune to the Elon Musk factor, tho; even if some idiot buys and breaks Bluesky-the-company, you'd expect more Blacksky-like thing to bud off.