Discussion of this close reason so far have been... pretty abstract. That's a shame; it's a waste of everybody's time.
These custom off-topic reasons aren't here to define the limits of what's on- and off-topic; that's what your help and about pages are for, and both should be informed by the discussion of specific topics here on meta.
Rather, those canned OT reasons are meant as a convenience, a way to succinctly explain why commonly-asked-about topics are not allowed here without needing to bother writing specific comments every time you have to close a question. As I wrote when we released this feature:
Don't try to brainstorm on what you think should be or might be off-topic. Critically examine what you're seeing in practice instead - this should be driven by the community, not by your own personal preferences or prejudices.
When we first released this, I sat down and went through a sample of off-topic questions for every site on Stack Exchange, including this one, and compiled a list of the specific topics that were closed. Then I picked the top 2-5 by volume and wrote custom OT reasons for them. I did not ask myself if I agreed with them or not - that's not my call; I just wrote the reasons to reflect the data. (If you're curious, you can find my initial OT reasons in SEDE)
Now, a lot can change in a year and a half; the common off-topic questions you get today may not match those I found back then. But I strongly recommend y'all follow the same process: look at the data, note the specific topics that are being closed, create pre-defined off-topic reasons for the most common ones.
You can do this using SEDE as well: http://data.stackexchange.com/serverfault/query/250376/off-topic-questions-past-90-days; if going through 800 questions doesn't excite you, then take a random sample and analyze that instead.
Triva: over the past 90 days, 43.4% of all closed questions were closed using the "must be relevant" off-topic reason. If you're gonna close everything with the same reason, there's no point in bothering with convenience reasons at all; conversely, if you're gonna spend the time hand-crafting custom OT reasons, they should actually be meaningfully distinct.
