If you haven't read Dan's previous article about Bitcoins security and the mining pools, I kindly suggest you give this article 10 minutes of your time to read through it.
http://bytemaster.github.io/update/2015/09/29/Bitcoin-is-100x-less-secure-than-commonly-believed/
While reading the article, keep in mind that the mining pools are a central point in the network.
There's no central point of failure in bitcoin.
There's a pretty clear central point of failure in Steem currently.
There is central point of failure in bitcoin.
Centralized mining. steem is 100x times secure than bitcoin in terms of central point of failure.