blockchain is a public ledger. There is no increased anonimity in it. Its core essence is that it is open and public, and everyone can check and validate it. The privacy part comes from not knowing which person is behind which wallet. But hey! You can do that here! Or anywhere.

Looking at the article:

According to Kolektiva, the seized database, now in the FBI’s possession, includes personal information such as email addresses, hashed passwords, and IP addresses from three days prior to the date the backup was made. It also includes posts, direct messages, and interactions involving a user on the server. Because of the nature of the fediverse, this also implicates user messages and posts from other instances.

Focussing on that last part first; Posts, PMs, and other interactions are open and public in the ActivityPub protocol (which lemmy and KBin and Mastodon work on). If the FBI wants that, they can just go to the website and make an account, no raid needed. Blockchain tech wouldnt chance that.

Focussing on the first part: email addresses, hashed passwords, and IP addresses, those are not all open to the public. And you may want to protect those better. But as I said, you dont need hip blockchain for that!

Dont use your primary email directly when making an account, but hide behind an email-alias. SimpleLogin, HideMyEmail, Guerilla Email, 10minute mail, Proton Pass, are all services that let you provide an email that is not your own, but does connect to your actual inbox.
Dont reuse passwords. Use a password manager to generate random ones for each website. Bitwarden has a good rep. LastPass is still used, KeePass exists, Proton Pass is new and promising.
Dont browse without a VPN.
bonus (use a privacy focussed browser with extensions that block un-whitelisted javascripts, block trackers, and block canvassing/fingerprinting).

Can your private info now still be obtained? The answer ranged somewhere in between possibly and probably. But you've made it a lot of work. Work that almost only a governmental agency can perform, in a way that takes manpower time and warrants. You'll have to have them very interested in you as an individual to go through all of that.

I compare it to going outside. You wear clothes so that you arent naked, shoes that protect your feet, and if you touch something icky you'll want to wear gloves. The internet is basically the same. Just remember, like outside, most of the internet is a public space. Information that you volunteer, conversations that you have are public. And differently from the real world, they are recorded forever. Need to discuss sensitive stuff in private, switch to "private places" such as encrypted email, Signal, or Matrix based platforms like Element.

Now this post probably isnt complete, and flawed. So I welcome anyone who wants to build further from it.