Only security experts can understand what the Windows system provides in terms of security, making it easier for normal people to get an antivirus from third parties. Not everyone burns their eyes reading
As with many things in life, there are many ways to achieve the same end goal. MS has made WD and Windows 10 very secure, but they don't always make it easy to understand, nor do they always make it easy to access. That's why 3rd parties are still a good option for some people.
Protection wise, I don't honestly think you can really see very much difference in the vast majority of products out there IMO. Even WD has improved enough to be a very good AV/AM, but it's still not perfect, nor is any other solution for that matter. As I've always said, it's not always about which product "scores" the highest on a test (including the HUB), there are many more reasons to choose a product (ie: performance, ease of use, configuration options, privacy, customer support, etc...). KIS is a very good product and is very simple by comparison. The settings are much easier to access/understand, however if you tweak WD and take full advantage of the security protections within W10, you will be just as secure, if not more secure by comparison. While it is much better compatibility wise than most 3rd parties out there, it's not always easy to access or understand, but at the end of the day both scenarios will keep you well protected, it's really a matter of which one works best for you and meets your needs.
In saying this, with the advent of programs like Configure Defender, H_C, Syshardener and OSA, it's far easier to take advantage of WD and the built in security within W10 than it use to be in the past, but it still does take some learning and understanding on what's going on.
All in all, like I said at the beginning of my post, there are multiple ways to achieve the same end goal, all it comes down to is which one works best for you.
