ASUS for example has a feature that 'optimizes' performance and enables it by default. Great stuff for the novice user, but not representable for stock reference proc results as they set the turbo bin to 4.7 GHz on all cores for the 8700k. The problem is that most reviewers do not even look at such settings to disable them (which I did for the reference proc review).
This is the part where Adored was right, but there's also a part where he took assumptions for granted: the part about chip quality and how 8400 will behave in the cheaper boards from Q1 2018. There were rumors among reviewers that initial ES chips were cherry picked and retail chips have lower quality than those used in reviews. Turns out some of them are indeed worse, but some are also better than ES chips - showing we're just dealing with expected variance.
Adored says he does not believe 8400 can sustain 3.8Ghz under 6 core loads, at least not the retail chips and not on cheaper 300 series boards (enforced 65W TDP and lower max current than Z boards). Problem is there's a very clear difference between being able to sustain these clocks in heavy duty loads like CineBench / Blender / Prime etc and keeping them up in usual consumer loads such as games, browsers, archiving programs etc.
I can understand why we should criticize the way some vendors chose to enable automatic overclocking on Intel chips, it's both unhealthy and dishonest, but I fail to see why some are taking this so far as to criticize Intel for allowing higher turbo bins than the chips might be able to sustain under very heavy loads. It's free performance for both users who choose to keep their chips at stock TDP (and benefit from those clocks in light loads) and users who configure their platforms for higher TDP to keep clocks up. Intel just offered consumers a form of limited overclocking on locked chips and somehow that's a bad thing... even though we received the fully unlocked chips from AMD with open arms.
I blame some of this on reviewers too: some of them simply turned a blind eye to how the platforms behaved in terms of power & performance, and only reacted when other more scrupulous members of the press began proper investigations on the matter. Kudos to Gigabyte too for adhering to proper stock configurations and indirectly helping make this issue obvious to everybody.