Dan was interrogating Vitalik, and, as we see, the scalability was a concern in 2014 and it is still the biggest concern of Ethereum nowadays. Another concern then and now is regarding using Proof of Work, which influences people to do useless work and makes the system centralized by miners. We saw recently for Status ICO that one token distribution was crashing the whole system, stopping other decentralized applications to work properly. Miners were abusing the system by processing some transaction first, so they can buy tokens cheaper during the distribution.
While Ethereum is still planning to address somehow that, Bitshares and Steem already have proven solutions. Bringing those solutions into an easy to use software to develop apps is why we need EOS.IO. Here I explain EOS in simple words.
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