This is all a matter a perception. Just like the 2018 6 core wasn't as bad as is being portrayed, 2019 8 core didn't become somehow a marvel of engineering overnight. It is the same machine as 2018 just with a different CPU - as it turns out it is better to run more cores at lower multicore clocks while rising single core frequency, with lower frequency you can lower voltage, power needed is proportional to square of voltage - you end up with machine that generates less heat. Add some undervolt and you get really good results - compared to 2018. Just like with 6 core 2018 you were getting much better results when compared to 2017 4 core in the same chassis.
When equipped with 6 core CPU (which doesn't differ in any substantial way from the 8th gen) you'll get essentially the 2018 version. Which is to be expected and there is nothing disappointing about it. Although there was nothing preventing Apple from undervolting the 6 core also.
The second factor is that the natural competitors of MBP - XPS 15 and X1E have not yet been released with the 8 cores CPUs, which is the opposite of what was happening last year. Once they're up it will be repeat of last year where the undervolted Windows machines with power limits removed will again be faster than Apple offering.
Notebookcheck has fallen down on my list of reliable sources, I see multiple mistakes or outright misinformation being produced - you need to be familiar with particular model to spot it though. They quote LTT now for crying out loud. I still look at their raw data, because they maintain some consistency in testing methodology, but they never address obvious discrepancies in results, like running a suite of tests on a gaming notebook in power saving mode.
