"In summary, when you strip away the fancy tech jargon like Directed Acylic Graphs, Internet of Things, and Tangle, what the IOTA whitepaper proposes is simple and fundamentally impossible. They are basically proposing that a blockchain with no difficulty adjustment can scale. When they actually implemented their system, they realized that this was impossible for an actual decentralized system so they implemented a centralized solution to fix it."
https://medium.com/@ico_8796/savedroid-ico-grab-bonus-tokens-now-with-new-marketing-tools-33e15358a331