No sybil attack protection. No spam protection. PoW is a fee in time and cost. But it's not scaling thus not enough to prevent sybil attacks meaning it's completely open. Its distribution used captcha method that was attacked as, once again, it doesn't offer sybil protection given ai and captch farms cost almost nothing. It uses delegation of stake instead of approval voting dpos have switched to because 1 account 1 vote is worst possible design method for representatives. it has same exact scaling issues as iota and blockchains by having to keep up with entire state of chain.

Bitcoin is important because it's secure. Steem tries to be secure by providing incentives and making it expensive and difficult to attack. RaiBlocks doesn't even pay its security nodes anything unlike miners or witnesses in steem meaning they have no reason to be honest at all. It's literally just badly copied old version of dpos with no incentives and a dag on top adding issues where they didn't have to be.

also, devs controlling most producing nodes is not a surprise. https://www.bitcoinbeginner.com/blog/raiblocks-needs-proof-of-stake/ but expected since there's no reward for doing all that work.