there's a couple of good historical mystery questions... just why did anyone bother to take potatoes and maize over to the old world to compete with existing crops? Someone with a merchant bent decide to bring in some 'exotics'? Potatoes I can kinda understand, it had a real niche as a garden crop that you could grow that no one would plunder/really bother with. But maize... sure, it's way more productive per acre than wheat, but did anyone really realize that back then?
I don't know if anyone did, but if they did, it wouldn't be grown in any appreciable amount and would be a mere curiosity until farmers at large adopted it. The opposition against potatoes is pretty famous, and it was still being actively resisted into the 19th century in places like Russia.
For maize, everyone already had wheat anyway, so why bother?
It probably wasn't but it's the only reason I know of (well, it also needs to be washed to remove something that coats the seeds but as far as processing goes that's not exactly hard). They actually went so far as to try to stop the natives from growing it.
Perhaps the reason that maize was treated differently was that it had enough appeal for them to overlook the religious connotations and/or a more pragmatic group of Europeans than the ones who had it in for quinoa were involved.
Not too far away from the Andes in Paraguay you had the Jesuits overlooking and adopting yerba mate cultivation on their lands despite the fact that yerba mate was for most all of the native groups in the area associated with religious practices.