If you are referring to this sample question I suspect the reason it was down-voted is that it is a simple definition question. We are looking to find good interesting questions that provide good examples for the site in the future. Questions that are potentially offtopic, or that can be found with simple search of the web generally do not fit that mold.
I do not think this question is off topic but it does not make a great question either. I did not downvote it but I would not upvote either. I think some quality econometrics questions would definately improved the earlier iteration of this site.
Excuse the strong language, but it is unthinkable not to include Econometrics in an Economics Q&A site. I understand that there exist economists who detest Econometrics (I have met some) -but there are also many who think that Economics without Econometrics is just an intellectual exercise for the fun of it (irrespective of where their expertise in the filed lies). Thankfully, they seem to complement each other.
As for the fact that Cross Validated accepts and deals with Econometrics questions, this happens because Cross Validated is about Statistics - and Statistics are used everywhere. This is also why Cross Validated has an abnormally high percentage of unanswered questions -they are so diverse and require so different kinds of expertise that simply, the required answering capital is not available. It will not be the first time SE sites overlap (for example, CV overlaps with math.SE as regards mathematical statistics and probability theory).
Many econometric questions in CV, rather than asking technical, mathematical statistics issues, have mainly to do with modelling (i.e. mapping the real world to a model) and interpretation. And for those, economists and econometricians are best equipped to answer. But also, for those more technical questions, I must note that there are many econometrics issues with which other statisticians are not really familiar with (and vice-versa of course). Econometrics is a very productive "offspring" of Statistics -it was economists and econometricians who first dealt consistently with non-experimental, observational data, brought in the surface the issues related to that framework, and studied them in depth, offering many important theoretical and applied contributions -and always linked with their interpretation for real world phenomena.
To provide an example that showcases the kind of interpretation of technical aspects that is needed in Econometrics: how many outside economics and econometrics do you think they have thought about what it implies (in abstract, I mean) to find a unit-root in two processes each describing the same economic phenomenon in two different national economies -as opposed, say to find a deterministic time trend? I get all kinds of surprised faces when I explain that it is the "unit root", this "symbol of randomness" that points towards a deeper structural (and hence "not that random") similarity between the two economies -while the deterministic time-trend just detects similarity in behavior (that may have a common outside source) and not necessarily in structure.
Econometrics is already covered by a tag in Cross-validated, so it may not be a good idea to create a site that overlaps with an existing one. We can follow a policy of redirecting users there.