timing is everything
The data they have looks back on some of the most stagnant years for servers, since essentially all of the data concerns Skylake and its minor revisions over the past what, 6 years? A few Broadwell too, which were in the same process. So, this is an era of pretty much constant clock speeds, constant memory footprint, and unchanging core functionality. Did not even get AVX-512 off the ground. The recent surge in AMD will have little impact on the data the accountants look at, and anyway Rome and Milan brought essentially no new functionality. Pricing is dominated by DRAM which has also been stagnant around $3 per GB for years.
So, look ahead and what do we see? A torrent of truly new chips. Made on new processes. With new accelerators on chiplets, and new functionalities like security. With memory perhaps finally shifting to lower costs via disaggregation, which will also apply (probably even more effectively) to "local" SSD. And don't forget the rise of in-house processors like Graviton-3 putting the squeeze on.
It will be very interesting to see if any current machines are salable in 4 years, much less 6. The road ahead looks like much more change in function and price than the road behind.