Are questions asking for feature sets of specific software versions on topic?
No.
The Q&A format works because it restricts what you can do with it. It has been tested and proved, and we went through many issues trying to figure out how to do a Q&A format. The fact that a handful works, doesn't mean that it will in every single case. The pure Q&A format is the only thing that we can apply to anything and everything, doesn't matter the circumstances and be glad that it will work.
Examples of this working shouldn't be taken as precedent for others to follow. That someone was able to use a hammer to bolt a screw doesn't mean that most will be able to. Lets stick with using the right tool for the job instead of experimenting with stuff that will eat our behinds sooner or later.
To illustrate my argument, is different to ask "Tell me all new features of X" or "What changed in X between 1 and 2" than "How to do Y with X" or "This thing I was doing in X.1 doesn't work anymore in X.2". The former have no re-usability. You can't point people with real questions to them, unless they are asking the exact same thing, meanwhile with the later can be used as canonical questions to solve problems that programmers really experience. This lists are potential several Q&A's going to waste, because someone was too lazy/didn't care to ask the right questions instead. That's my main problem with them. A very expensive luxury question that nobody will use in something practical, to solve their issues and will set a bad precedent, instead of a potential 20~30 Q&A that can help several thousands to solve their problem.
P. S. : when I googled "register c++17 not working" as it was removed in the latest implementation of C++, I got some relevant results, one of them a SO post asking for, well, a replacement, which is the kind of questions we should encourage. When I googled "node.js 0.12 how to use proxy" I got 0 relevant results. These questions ain't helping people to find solution to their problems.