Those tests mean nothing to me, I know some happy clickers but I don't know any who got a thousand malware samples on their desktop. These tests bypass many layers of security solutions and simply test file system protection. Yes, Windows Defender is improving and yes it's a good thing that users who would never install an AV have Windows Defender running in the background offering basic protection. The problem is the performance, the bugs and how easy it is to disable like seriously, one UAC prompt a user clicks unknowingly and Windows Defender is disabled (and that's if you have UAC Always On which most don't). I'm glad that Microsoft are upping their game and making Windows more secure out of the box than it has ever been, but a multi billion dollar company could do so much better...
When I reinstall Windows and Windows Defender is enabled it feels like my gaming PC is a 10 year old laptop, you don't understand the difference I feel when I disable it via group policy and install ESET.