Considering Target has been the brute of the difficulty, as far as I can see, in amiibo gathering, I find them to blame.
Any amiibo gamestop has is always easily available- they alert customers of both preorders and arrival, provide multiple ways receive the items, and often reopen the time table for another wave of an already released amiibo.
Target and Walmart are the ones who, knowing the difficulty of this item, just make it available whenever they so happen to feel the decision is within them, making predictability of online purchasing times, much less in store stock, a completely random event. There is no way to stay on top of those two stores.
Even Best Buy and Toys R Us had their preorders open for over a month with their exclusives.*
I may be remiss to reform my previous post in stating this is not all Nintendo's doing, but it certainly and in large part, a failure of the retailers.
*I don't think it is acceptable for consumers to bemoan an overall lack of availability for Shulk, Meta Knight, or Lucario. If it was sold out from under you, or in other ways removed from your ability to actually secure a product deemed just- then I would likely agree. However, figures like Meta Knight were available from November 21st until at least January to preorder. Lucario could be found both in store or online for more than a month. Shulk, as well.
Only Jigglypuff (thus far), Rosalina, and Gold Mario are in any comparable state of 'retail failure' in the US.
Any other figure that a customer did not get here, I can honestly say, they just did not want them badly enough. Even when we did not know about the short supply of them, 12 days after release, when Villager/WFT/Marth were cancelled everywhere- if you did not get it the first ten days, you considered them too informally. I was even one of those in the mass who did this with Marth and Villager- I put off getting them.
Well, after that, no more did I do such.