In the article, they draw conclusions from the direct comparison of the annual evolution of graphics card sales figures.
And as the Hardware Enthusiasts know :troll:, these figures are mixed with economic trends (crisis), the growth of console use over PC (games), and software optimization (Intel iGPU especially).
Crisis = fewer sales in general, hardware lasts longer (gamers update their graphics cards less, and business computers with low-end graphics).
Games = you can already play almost everything in 2D with integrated graphics, indie games and emulators, and the growth of consoles (because it's easier than playing on PC :D).
Software = you can already use integrated graphics to process video using its native instructions, and for casual 3D, almost anything will do, better dedicated, but it can be old.
Salu2!