Wrong. Bitcoin payments processors report growth, eg. BitPay processes $1 billion in payments per year, up 328%! https://blog.bitpay.com/bitpay-growth-2017/
The source you quoted is laughably bad: it tries to estimate payment growth by looking at how many of 500 retailers accept Bitcoin. That's like saying "out of 500 persons only 3 own (not bought) a Porsche this year compared to 4 last year, so worldwide Porsche sales are down."