Edge still has a spoof referrer header vulnerability that's been known for more than 6 months now: https://www.brokenbrowser.com/referer-spoofing-patch-bypass/
More generally, there's a lot more to making the web great than a blind sprint to adopt every API. Just because it isn't shipping doesn't mean Microsoft isn't a (very) active participant in the standards conversations, testing behind flags, etc. That is a huge part of moving the web forward.
Take Grid as an example - we were the last browser to ship the updated spec, so you could say we "held it back." But we also originated the first version of the spec and worked closely with the community, standards bodies, and other browser vendors on making sure what ultimately shipped cross-browser this year was great, useful, and interoperable. Is that holding the web back?
(Disclaimer: Edge employee)
I've never used Edge and have no particular interest in it, but html5test is basically a way for Chrome users to feel good about themselves.