What is shown there? From their website, I think it is this:
„This graph counts the baselines submitted to us during these time period and therefore is representative of CPUs in use rather than CPUs purchased.“
So IMHO it is rather CPUs being benchmarked & their results submitted during the respective time period. You can draw your own conclusions as to what this says. I for one do not benchmark my home system on a daily (or monthly or even quarterly) basis, when I do not change it's config.
Yep, clearly not representative of sales, it just shows a huge uptick in enthusiast interest in AMD. It could also be that Ryzen users benchmark their systems 5 times a day to tune memory settings, however.