Also for probably not the last time, API calls made by addons are strictly throttled to “human” levels. Blizzard has used this throttling model for ages and any issues with it are not an addon problem; they are a Blizzard backend scaling or coding problem.
Blizzard knows from DF exactly what the “beginning of expansion” load will (would) be. The AH model (region-wide commodities, per-server everything else) was the same as it is now all the way through DF. Take DF, add 20% or 50% or whatever based on sales, that’s your scaling right there.
Again, if it’s a load problem, it’s the fault of the company providing the service, not the users paying for the service. The load the AH is experiencing now is entirely predictable from the previous expansion.
But given the sometimes terrible performance of the AH 2 months ago when there was almost no one playing, I think that any outages probably have an entirely different cause unrelated or at most indirectly related to load. Heck, Blizzard even stopped updating the AH game data API for several days a couple months ago. That was certainly completely unrelated to load.
Also /ignore.