The only computers running Windows that I manage or own only have server editions on them. I've come across many, many bugs, crashes and other annoyances in the betas and release candidates, and I'd really love to report them properly, but the Feedback Hub seems to simply not exist nor function on Windows Server 2019.
Is this really the case, or should I simply post it all here and trust that it's taken "as seriously"?
Unfortunately you are correct, Feedback Hub is not available on Windows Server. To submit through Feedback Hub it needs to be on a Windows client machine, I apologize for the inconvenience. This forum is for issues and feedback of the future development of Windows Server with the builds being posted to the Windows Server Insiders. There are other forums for released products (for example WS2019), and this forum is focused on vNext. If you are encountering crashes and such with shipped product, opening a case with Microsoft CSS support is the best resource. They can analyze dumps and help drive resolution to any issues you are encountering. Also any support incidents related to bugs in the product are free of charge.