[pollen23]

It's not run by "a set of trusted third parties".

It's run by SETS of trusted third parties, where each individual node specifies what set of nodes it trusts to not collude against it.

You don't need any ones permission to run a node, but it is up to other nodes if they want to trust you

[CryptoPunk]

If your set is not the same as everyone else's set, you risk being forked off. Trusted third party based schemes have a tendency toward centralization, making them less resilient than ones based on cryptoeconomic incentives. Inevitability it will mean TTP based ledgers will be permissioned, with the TTPs acting as gatekeepers, rather than p2p.

This isn't just theoretical either. Stellar has co-authored a paper arguing for regulations against anonymous cryptocurrencies:

http://www.lhoft.com/assets/uploads/images/WhitePaper_LHoFT_...

It's clear that it's positioning itself as a gatekeeper-based ledger that stays on the good side of regulatory agencies.