1) Google generally doesn't answer support requests, they let a random Google Group handle it for "community support". (Unless you are an Apps customer in which case you might expect a reply somewhere between a week and a two years later, and it's still recommended you try the "community support" first.)
2) This isn't a "We won't support you, use at your own risk" banner, this is a Chrome ad. It's a Chrome ad disguised as a support banner. It's a Chrome ad that is designed to get ignorant users to install Chrome out of some fear. This is no better than those "Your computer is unprotected, install this fake anti-virus to fix your computer" malware ads you see everywhere! Sure, maybe Chrome isn't malware to you, but it's unneeded confusion to, say, my grandmother, to have her browser suddenly change because she installed a thing Google told she had to to stay "supported"...
3) This is a case of "Proprietary" versus "Proprietary" on Windows: Chromium is open, Chrome is not and especially on Windows has adware and custom extensions that are fairly opaque and proprietary. On the other side of the fence: Edge's JS engine (Chakra) is open source and community developed, and Edge's WebGL renderer just became open source. Edge is already more open and standards compliant than IE ever was. Blaming Edge for IE's old problems is like kicking your new puppy for things your recently deceased dog did.
4) Yes, as a web developer, I remember bad experiences with IE's implementations of standards, but unlike some I also remember some of the good experiences. I also am aware enough as a web developer to know that IE's "bad" implementations helped make the standards better. Plenty of people can talk about how IE contributed XHR and AJAX. Another example is that "box-sizing: border-box" you see littered throughout CSS these days is "Hey, use the modern version of the classic IE way because it is easier to math." The point of the "Open Web" is not that "mistakes shouldn't happen and standards should be implemented in lockstep", it's that anyone can and should implement the standards and when the implementations don't agree we use that to make the standards better! Chrome owes a legacy to IE, and "bad experiences in the past" don't outweigh the benefit to the Open Web today by not interfering with users that choose to use Edge regardless of whether or not that's simply because it is Windows' default browser.