I don't really agree with the review in the sense that DDR3200 is the baseline... I would say its actually the sweet spot. Unless you have spare budget which cannot be used for anything else, then you spend it on upgrading your RAM.
Of course, what I am saying applies to mainstream users. If you are running photoshop or premiere or do video encoding frequently, I wouldn't consider you as mainstream user.
I think it depends on what we understand as "baseline" and "sweet spot".
In that sense, I do see DDR3200 as baseline (a speed to start with). It doesn't really make sense, that someone who buys 5000 series CPU, would buy slower RAM -especially because price difference is quite small.
About "sweet spot"... just need to say I don't like that "fancy" term -because it tells nothing. Saying that, next step above "baseline" would be "advanced" or "professional" use -where DDR3600 suits best for performance and stability.
Fine article, but does this differ much from previous Ryzen generations? I was under the impression it was sussed out already, RAM speed matters more with a Ryzen CPU than it's direct market competition, and 3200 MT/s is nearing that point of diminished returns. Yes, you can gain more, but the cost benefit analysis doesn't pencil well so one makes a personal judgement call whether to invest further. There is more performance to be had, but whether it's worth it is hardly something I would decide for others.
I think I stick to what Hardware Unboxed memory tests shown already. Plenty of videos on their channel.
About dual ranks vs single rank HU already proved that dual rank is faster most of the time and enough to be worth it, especially in gaming.
They also showed that 4 x 8GB SR sticks will work as DR automatically when used together. That's why it shows this even in your graph, but you failed to underline that and thus your conclusion was wrong. Or you just don't know, plain an simple.
As for frequency and timings these are by now almost accepted as an unspoken law:
3200 is base, 3600 is the sweet spot and anything above that is for enthusiast class.
CL 18 is max accepted only at high frequencies, CL 16 is base at any speed and anything below that (CL15, CL14) is again, for enthusiast class.