Let's just take a moment to share Wikipedia definition of DevOps (emphasis is mine): "DevOps promotes a set of processes and methods for thinking about communication and collaboration – between departments of development, QA (quality assurance), and IT operations".
Some might disagree with Wikipedia's definition, but many places will have a similar definition where they say that DevOps is about processes, communications, methods, and sometimes tools and/or automation.
Therefore, I firmly believe that a DevOps stack exchange site should allow questions that evolve around all of these topics (including the promotion of these topics), not just a subset of them.
However, we must be careful to have clear guidelines that makes it clear how to write good questions to which we'll be able to write great answers. Based on the StackExchange format, it's better to have questions that can be answered rather that indefinitely discussed based on everyone's preferences.
It is totally possible to have mindset/cultural/process/guideline questions that can be answered. A question about process or methodology is not inherently vague, though it can be.
To give concrete examples, I would vote for questions like:
- "How to build a DevOps mindset?" as being too vague (and it's not like there's no article on the Internet discussing the matter).
- "How to communicate the benefits of automated deployments to high management?" (where the question would details why the high management at CorpCo doesn't want to invest in automated deployments) as a good question because we can give very precise answers to such a question, addressing the key issues raised within it (eg.: management thinks that it will take too long to build)