I like the wiki definition
https://en.wikipedia.org/wiki/Decentralization
Decentralization or decentralisation is the process by which the activities of an organization, particularly those related to planning and decision-making, are distributed or delegated away from a central, authoritative location or group and given to smaller factions within it.
Based on this and other definitions I've seen, Bluesky is NOT decentralised.
I struggle to see how a platform of which 99.96% of it's users are controlled by one entity is Decentralised.
Blaze@lemmy.dbzer0.com 1 day ago
Top Provider User Share: bsky.social ≈ 99% → Score: 0/30 Top Provider Content Share: Nearly all content on bsky.social → Score: 0/30 Self-Hosting: Server: PDS hosting possible but very niche and poorly documented → Score: 4/20 Self-Hosting: Client: Mostly official client; some 3rd party → Score: 10/20
Total: 14/100
Interesting score
Ek-Hou-Van-Braai@piefed.social 1 day ago
The scoring system isn't perfect, and is subjective, but it's a good starting point to try and measure if something is decentralised.
I forsee a lot of big companies pretending to be Open-Source and decentralised because it's good for profits. Just like they pretend to care about Gay rights etc. When it suites them