Related to a subset of #696 that won't be fixed by #828.
If a solution build has a RID specified, it will fail.
This can be because (after #828) it double-builds a library (once with RID specified from the solution's global properties, once with it removed):

Or, if nothing is done, this will fail when attempting to specify a RID on a project that doesn't need one.
If VS and the CLI distributed a solution-extension target that ran before Build and errored when '$(RuntimeIdentifier)' != '', it would at least provide guiderails to nudge users back into the more supported scenarios. It could say something like Building a solution with a specific RuntimeIdentifier is not supported. If you would like to publish for a single RID, specifiy the RID at the individual project level instead.