I'm not being hyperbolic, $300 in 2015 buys you a better graphics card than $300 in 2018.
In normal times, a $300 card in 2015 costs $150-180 in 2018. It's easy to then see that the 2018 $300 card much be generations further.
However, today, a nVidia GTX 1060 will run you around $350 if you can find one in stock, and its performance per dollar is literally inferior to say an AMD R9 390 from 2015, which could be found under $300.
Very rarely in tech do we exist in a market where 3 years ago performance costs more today than it did then.
Would you be okay paying $600 or $700 for an iPhone6 or LG G3? It's shocking to us when years and years go by and your dollar doesn't change what you get.