Irrelevant how? May mean nothing how? I think it is relevant and means something, regardless of the edition size.
Like I said, I think regardless of how many were made, sold out means it has met if not exceeded the sales target of the manufacturer. And these manufacturers as well as their distributors of course, know which franchise would sell more, and would produce more of these hot-sellers. While selling out would have to be the ultimate goal, I'm sure they have a more realistic sales quota. This is similar to the DX08 Nicholson Joker, that's still around. It's not sold out, but does that mean it didn't sell well? If so, why did HT come up with DX14 based on a less anticipated version of Nicholson Joker if it only meant another poor-selling figure?
It's possible that HT produced more of DX08 than other figures, for some reasons, that's why it still hasn't sold out. But who's to say that HT didn't meet or even exceeded their sales target for it?
I think, at this day and age of collecting where "limited edition" is not as limited as before, what's irrelevant is the edition size. What matters is if the manufacturers would break even, sell as much or more than their target, or sell out.