I believe questions asked at Stats.SE about artificial intelligence should be on-topic here as well, because:
You may suggest they may lacking of AI experts there, so lets move there. However not all AI experts are using or are interested in statistics models with AI.
For example I'm no where near as statistician, I've no idea about cross-validation aka rotation estimation models, but I may use and implement practical AI algorithms.
Therefore I think our site has already its own distinct and unique scope in comparison to Stats.SE, because it is about pure Artificial Intelligence and beyond.
You can still asks about AI at Stats.SE, but it should be focused to statistical learning. To support that, check this post:
Question on AI including a comparison with statistical learning would be pretty clearly on topic here.
They were accepting even without that, but I think most likely because people didn't have the right place to ask. If they've asked, didn't have much attention (maybe AI experts aren't interested in statistical models).
If you've question about theoretical AI, you can consider asking at: CSTheory.SE (not active either).
We can only hope that after 6 years of previous failures, we're able to break some ice this time.
We've one-time final opportunity to not have AI spread across the whole network:
Stats.SE, CSTheory.SE, CogSci.SE, Philosophy.SE, Worldbuilding.SE, SO.SE, CS.SE, HSM.SE, Robotics.SE, GameDev.SE, gosh where else, with no real AI experts in one place.
So basically the goal of this site is as pointed by @lejlot:
To bring people from this one particular field, which exists in
between all above in one place. I see the reason behind it - as now
questions regarding AI are scattered across these sites and get very
little attention from actual experts, who also visit just a subset of
these. Additionally - on each site these questions are tagged in a
different way, so it is impossible to track them. Unification (new
site) would make all of it much easier (and in fact - possible for the
first time).
If this going to fail this time, people still will have to have 10-20 different accounts to ask the right questions on the right sites (which is very inconvenient). This would be very sad.
To summary, some say:
statistical learning is not the path to AI (Artificial Intelligence)
but it's open to debate.