I don't think Blender 2.8 related question should be automatically considered offtopic. It will eventually become the official latest release, so it should be encouraging to have early answers and clarifications about it.
That is as long as they are not about trouble shooting technical problems with the builds themselves, along the lines of "Why isn't this working?" or "Why is behavior X unexpected?", or "Where is < favorite missing feature >?" and the typical "When will it be ready?".
As iklsr politely mentioned, the currently available builds are highly experimental, still broken in fundamental ways, and not at all ready for prime time. They are not Beta builds, nor Alpha, not even ready for public testing. Expecting them to work at this point is unrealistic at best.
Generally speaking those may even be considered bug reports of sorts, which are a widely known type of off-topic here.
Once released I'd expect all kinks to be ironed out, making such questions validity and relevance questionable for the long run too.
One other concern I'd personally have is that encouraging end users (especially beginners) to use these as production software, which may lead to an increase in unwanted bug reports in the bug tracker, which already is managing hell for the scarce developer manpower.
At this point I fear end user bug reports are more of a hassle then helpful. Quoting Sergey Sharybin from the bf-committers Blender 2.8 meeting of August 15 2017 mailing list
Note for everyone: Blender 2.8 tracker is currently for developers to
coordinate core development. We can not spend time on fixing users
reports yet: lots of them are requiring core parts to be finished
Besides the obvious dangers of potential data loss while using untested pre-alpha software.
Questions along the lines of general usability, or theoretical questions about officially known features and roadmap, should be OK, I guess.
EDIT: And here it is, the official statement of what I have been trying to convey, The message at the official 2.8 snapshots download page has been changed to request bug reports exclusively from developers. My point being we should prevent random users from reporting bugs at all costs, even at the expense of testing 2.8 nightly builds by not encouraging end users to test them at all.