It just needs to be updated from scratch using a standard test suite of games and/or benchmarks. Preferably weighted with newer titles so the older CPUs drop out of the top tiers.
I don't think anyone really has the time or components except a few professional reviewers. And they usually do some reviews with something specific in mind. Like saying how good is the i5-3570k compared to today?
And to be fair, you can still run most games with an i5-3570k, not ideally, but it will at least work.
Same with the legacy GPU chart. The most common questions I see regarding GPUs aren't possible to answer on that chart. Always wanting to know if their OEM or worse integrated graphics is on par with some other obscure card. A lot of effort to get all the mobile devices on their, and given the control OEMs have over clock speeds, power output, and cooling, hard to be definitive.
I find myself relying more and more on user benchmark...at least for low end stuff. Gamer's Nexus for anything worthwhile (They go into almost too much detail). But I also find annoying gaps in even their data.