Is "closer match to another SE" a reason to close an on-topic question as off-topic?

Question

This is related to Close as off topic, flag to migrate, or both?, but it is specifically about questions which are on-topic where originally posted.

The SE family is getting quite large now, and a lot of the time a question could be in scope for more than one SE. For example, a few months ago I posted a question to Biology.SE, which (and this is the key point) was on-topic for Biology.SE, but was felt to be even more on-topic for the relatively new History of Science and Mathematics SE (which I would agree with, although at that point I hadn't come across HSM.SE). It was closed using the 'off-topic' reason and a comment was left saying "I'm voting to close this question because it would be more appropriate on the History of Science & Math Stack Exchange site". At this point the question was already receiving attention and there was no reason to think it would not be answered satisfactorily at Biology.SE.

My question is: If we see a question that is on-topic for the SE it is submitted to (and receiving attention), but there is a second SE for which we think it is a better match, should we be voting to close - as off-topic, or as anything else?

Another example: we now have a Bioinformatics.SE (which has a total of 575 questions), but we also have 795 questions on Biology.SE tagged as bioinformatics. Should those questions all be closed as better suited to Bioinformatics.SE? (They're too old to migrate now.) If not, why not? Has bioinformatics become off-topic for Biology.SE now that Bioinformatics.SE is a thing?

I could also see a risk that this resulting in borderline questions ping-ponging between sites. For example, I could see this one being closed on History.SE as more appropriate to Biology.SE, and then vice versa, if History.SE hadn't accepted it.

In the answers to the related question I notice a suggestion that you only propose migration if you have a rep of 1,000+ at the proposed destination, since it can take a while to get a feel for what sorts of questions are in scope.

(If anyone really wants to see the question that prompted this thought it's here, but I'm not asking about this question specifically and I'm not pushing to have it reopened - this is purely for interest.)

Answer 1

From What is migration and how does it work?:

We only migrate questions because they are off-topic on the original site. It is perfectly possible for a question to be on-topic on multiple sites, but that is not a reason to migrate it elsewhere, unless the OP requests migration. As a general rule, if someone asks a question here, and it's on-topic here, it should stay here.

So that would be a no.

Has bioinformatics become off-topic for Biology.SE now that Bioinformatics.SE is a thing?

I think that's something which is up to the sites themselves to consider.

Answer 2

In general, an ideal migration is off topic on a site, is excellent and completely on topic elsewhere. As a moderator of an early site with a very broad scope, I typically would reject migration suggestions of the form "would be better on othersite.stackexchange.com" if its on topic for us.

Migrations are contentious - there's been talk of dropping the whole process in the past, and some sites tend to do bad migrations more than others.

You can't ping pong a question - a rejected migration stays closed on both sites. In theory there's a path we can take to migrate it elsewhere but if a question is rejected by the destination site - it isn't going back there.

I'd also add we don't typically migrate to new sites simply because we don't want them to rely on migrated questions. They need to get their own userbase, and work out their own scope.

So no, if its on topic, for the love of dog, don't close it or flag for migration somewhere better.