Really anyone reading this would think x570 had the feel of earlier unfinished AMD platforms ...
In first iteration memory not working properly, memory compatibility terrible, vrms often of sub standard, paper feel of thin pcbs, not all ofcourse but many took bios revision after revision after revision or even hardware revision....
Now all X570 I tried run 4266 mems, some 4800 stable.. They are running 4x8 or 4x16 3600. Solid vrm. Premium look and feel, not like a sheet of A4.... No one is commenting on the new found quality for an AMD user...
They are commenting that they are expected to pay for this quality....
If this was an Intel X platform no way do people kick off so hard for obvious leaps forward in quality across the range.
3600 or 3600x plug and play in old boards even b450 works fine.
I had R7 1700+C6H on pre-order at launch. At that time there was very little tuning/tweaking features, from posts by The Stilt, Elmor and Raja@ASUS it was clear AMD had launched prior to reaching a "ripe" state. Even though the ASUS UEFI had RAM timings section it did not function, as AMD FW was locking out vendors from changes, Elmor explained this.
Within a month or two we had flood of options to aid tuning/tweaking. Between all these options appearing and launch, The Stilt had posted whenever anyone queried aspect of RAM speed that we probably have not yet seen the limit of IMC, once all the options were there, was when he started sharing his take was 3466MHz was about the max decent 1xxx series would do where high stability was needed.
Fast forward to when I go ZE at launch and it was clear Threadripper benefited from delayed launch. All the UEFI options were there, if I wanted to tinker with RAM and or CPU PState I could. So IMO all the info The Stilt, Elmor and Raja@ASUS had stated in the C6H thread at launch, stating platform was not really ready for launch and needed 3-6mths "baking" was correct.
When I got 2700X+C7H at launch, I really had no doubts that I'd see vast differences/gains over UEFI releases, as pretty much now Zen/+ was "baked and ready to go".
As far as I know, even now AMD do not allow mobo makers to tinker with CPU IMC FW like they can with Intel. I have compared sections of AGESA ComboPi-AM4 1.0.0.3 relating to this. The Stilt highlighted this issue while back,
link. Another tid bit from The Stilt was the reason on Ryzen we can't change RAM timings in OS like on Intel, is as AMD locks this out, only at POST can RAM timings be applied. So I really think mobo vendors are more so just mopping up issues with their side of UEFI and integration with AGESA, rather than tuning AMD FW as they would for Intel board, as they are locked out.
I do believe the ease at which you are seeing RAM hit the speeds it is and compatibility is more down to 3xxx CPU IMC than X570 being higher quality vs X470/X370, leading to improved RAM MHz/compatibility. Caveat being the more top end speed maybe aided by say 8 layer PCB/improved tracing, etc. Again though the 8 layers is only on higher end X570, I saw a site have info where it showed only 2 of the Gigabyte boards having 8 and rest are 6. So I would expect a decent X470/X370, for example 6 layer PCB to hit very similar RAM speeds as X570. Especially as AMD will have control on aspect of FW relating to CPU IMC.
This post is not meant to detract value from your shares, nor to discredit your take, more so just what my take was.