Hello, You're receiving this canned (template-based) bug report because I found an annoyance with a package during my tinderbox run. The package in question is checking for one out of a series of USE flags to be enabled, likely because these are multiple selectable backends, but it currently does not use the EAPI=1 feature of default USE flags to work out of the box. You can see in my blog post in the URL field why that's a pro
You are right, but this is sadly a WONTFIX. There is no sane default, because it would be arch specific. And I never heard from arch specific default USE.