I only have seen statements here from Intuit employees, repeatedly, indicating that QB 2015 and 2016 ARE supported. Usually this is followed by a request to the OP to upgrade to 2016 for use with Windows 10. So, to me that indicates that it is supported. Also, I Googled it and came up with this: <a rel="nofollow" target="_blank" href="https://community.intuit.com/articles/1201230-windows-10-faq">https://community.intuit.com/articles/...> On this page it is very clearly asked: "What versions of QuickBooks are supported on Windows 10?" And the answer starts with: "QuickBooks 2015 and later:"
Where do you see the statements otherwise, as they would seem to conflict with Intuit's own support team?
RE: "...but your retort "what do you mean supported" should be clear when it comes to software"
It's a question, not a retort. I wrote, "What do you mean by "officially supported"?", and by that I mean to ask exactly that, because I don't know what you mean. In turn I think I don't know because I don't think the phrase "officially supported" has a very specific meaning. One meaning could be that Windows 10 is included in a list of supported OS's. Another could be that Intuit states it is supported, which they have in more than one way.