Is there anything about Farcaster being decentralized that uniquely lends itself to frames being possible, or could the same concept be built on a centralized social platform?

Nope. Frames could work on X or Bsky. Expect both to have some variant at some point.

Working on Farcaster and Warpcast. Longer thoughts at https://dwr.email

The only moat is a native farcaster token

Why not decentralize early to onboarding more crypto mindshare and differentiate against X + Bsky? Why isn't this a higher priority?  

E.g. I know devs in SUI + Algorand who both thought about building on FC but chose not to because of its singular alignment to ETH