[fabian2k]

The actual rule here is about question where every answer is equally valid, so asking for pure opinions (https://stackoverflow.com/help/dont-ask). Questions that have multiple potential answers are valid questions in general.

There are questions that are somewhere in between, something like "which approach is better here?". Those tend not to go well on SO even though they theoretically could be on-topic. This is a case where the community is sometimes overzealous, but it's extremely hard to consistently apply these rules to complex edge cases. And many questions of this kind do not fit to the rules and are closed correctly. These questions usually require quite a bit of familiarity with SO to formulate them in a way that works on the site.