I think peoples’ issue with it is that it’s not just inaccurate, it’s wildly inaccurate – not just due to limited data, but to incorrect calculations. Maybe someone else knows more about that, I’d like to learn how it values properties.
A friend of mine has a house in Vista with a zestimate of $1.3m (and climbing, according to zillow), and he’d be lucky to get $1m for it today.
I don’t think it will ever threaten appraisers – it doesn’t store enough data about individual homes, and has no way of finding that information out without human intervention.