Blockchains that rely on some form of master nodes (or "witnesses"), like Bitshares, Steem, Ripple are a different category altogether, and as they practically are variations of the Paxos algorithm, they could have been around for about 20 years already.
Satoshi's main innovation was actually the complete trustlessness, in that everyone can run a node (miner) without having to ask anybody, or without being referred or being elected or delegated by anybody. The downside to this is that it makes things like scalability much harder.
But nevertheless, the fame of Bitcoin probably caused a revival of many of those older distributed technologies.
That's not to say that each approach has their own place, their own niche of course. Use the best tool for the job at hand.
Might you be able to recommend any great resources to clarify the distinctions between the different tools and simplify the differentiating factors between each?
It's hard to find any specific literature of the distinctions and comparisons, but the irony is I've been wanting to do a "Battle of the Blockchain" presentation for our local meetup group when I get around to put everything together, and no, I didn't steal the title from you.
;)You should write a piece on it. Would be useful for everyone.