You made a mistake in your article saying that techniques that allow using the hard disk for mining are called Proof of Stake. PoS is an algorithm that works under the principle the more cryptocurrency owns the miner, the more power he has. What you described is called Proof of Capacity. Burstcoin is practically the only coin that uses PoC that makes it attractive for miners. Currently, cryptocurrency is in uncertain conditions. It’s not very popular among crypto investors. Probably it relates to the low market cap, PoC technics can change the situation nonetheless.