1.4v vcore is probably too much.
The article said under 1.4 - although how much may vary.
So they're not selling the 3600x or 3800x, maybe because they're factory binned (3600/3700) well enough already. Correct me if I'm wrong, but one complaint was that enthusiasts don't have much headroom for overclocking zen 2 chips because they overclock themselves well enough already. Seems more cost effective to buy the higher TDP 3600x/3800x and try to overclock than to bother with buying a "binned" version from vendors like Caseking.
No, they're doing it right. So the 3600X and 3800X are already binned tight, but they cost more. So your chances of getting a good all-core overclocker might be a little higher, but the difference between an "ideal" and an "average" model are SLIM. You can't mark them up much, so your margin will likewise be slim. Meanwhile if you buy a crapload of the cheaper models, a bunch of them will end up being just as good as an "ideal" higher-end model. Since they paid far less, they make more money per chip, and buyers get a guaranteed clock plus a warranty. They've got multiple guaranteed bins so I'd bet a large number of their chips fall into one of those bins. Meanwhile the ones that don't clock great they can resell and/or sell in stock-clocked prebuilts.
Personally though I don't plan on doing a manual all-core overclock this time around. The boost/auto OC pretty much milks most of the chip's potential, and I'm content to just do a lone-chip gamble and I get whatever I get. That way even if I just end up with a couple decent cores in the whole chip, that's fine - most games still lean hardest on 2-4 primary threads. Even if they scale well, beyond that, it's not perfect. Not going to go radical on power, either, whatever the chip and board let me get out of a good aircooler.
So yeah, the guaranteed bin isn't for me. But I understand what they're doing and buying the less expensive chip is the right approach if you buy a bunch of them and have an outlet for the units that don't all-core clock well. I will be curious to see if clocks improve over time as the process matures.