AFAICT #ATproto thinks of a PDS like a website. #bluesky is decentralized like the web cause lots of fully independent PDSs exist, like most websites are independent. Having very few relays or app views is fine like it's ok that other things on the web are more centralized. DNS, search, email etc.
Not at all.
Social media is not about content but connections. The parts that determine reach and what can be boosted. The ability to go viral. Those must be decentralized.