Alexa pulled talent from everywhere throughout Amazon. It took up a huge portion of the hiring funnel for new devs. All of those people could have been doing useful, money-making, cost-cutting things instead.
I can think of at least a dozen really brilliant devs I worked with in Amazon Fulfillment who left to go work for Alexa. They'd tell me what their team/group/org did and I'd ask "but how does that make money?" and they'd laugh. "Yeah, last year I heard we had less than a million in revenue, but hey, they're certain it'll become big somehow".
What a waste of talent.