I was initially surprised by this article, but I have found that the cost of the equipment is now a major factor. The difficulty is so high now that an S9, which costs over $1000, hardly mines anything any more.
The cost of the hardware has always been a bery big factor ever since the beginning. One of the main problems of mining Bitcoin is how volatile the price is, which chanhes your ROI time significantly while not having absolutely any control over whether you actually profit or not. It has always been just a gamble since your fate is in other people's hands.
While the exchange rate has been going down in the last couple of months, I believe this has been a good thing for some parts of the market. I work with video editing on a personal, and sometimes professional level. I also like to game ocassionally. When the value of Bitcoin went down, other cryptos went down with it as well, and so did the profit from buying graphics cards to mine those cryptocurrencies. With the fall in demand, the prices started falling back to what they were before, which I personally consider a very good thing. Same thing goes for memory. I have not tried to do the math behind where the threshold is for altcoins, but it has definitely had an effect.