This is a change in ARIA 1.1. In ARIA 1.0 the listitem role could have a name from contents. However, in ARIA 1.1 this changed. I'm not sure if following the rule change will break AT experiences. I filed an issue on the ARIA spec for clarification as to why the rule change: https://github.com/w3c/aria/issues/581 Whatever is decided, it should probably apply to <li> as well.
This is something we should triage and fix but isn't among our most urgent bugs.(Contributions welcome as always!)