Remember Tay, the chatbot Microsoft unleashed on Twitter and other social platforms two years ago that quickly turned into a racist, sex-crazed neo-Nazi?

What started out as an entertaining social experiment—get regular people to talk to a chatbot so it could learn while they, hopefully, had fun—became a nightmare for Tay’s creators. Users soon figured out how to make Tay say awful things. Microsoft took the chatbot offline after less than a day.

Yet Misha Bilenko, head of machine intelligence and research at Russian tech giant Yandex, thinks it was a boon to the field of AI helpers.

Speaking at MIT Technology Review’s annual EmTech Digital conference in San Francisco on Tuesday, Bilenko said Tay’s bugs—like the bot’s vulnerability to being gamed into learning or repeating offensive phrases—taught great lessons about what can go wrong.

The way Tay rapidly morphed from a fun-loving bot (she was trained to have the personality of a facetious 19-year-old) into an AI monster, he said, showed how important it is to be able to fix problems quickly, which is not easy to do. And it also illustrated how much people tend to anthropomorphize AI, believing that it has deep-seated beliefs rather than seeing it as a statistical machine.

“Microsoft took the flak for it, but looking back, it’s a really useful case study,” he said.

Chatbots and intelligent assistants have changed considerably since 2016; they’re a lot more popular now, they’re available everywhere from smartphone apps to smart speakers, and they’re getting increasingly capable. But they’re still not great at one of the things Tay was trying to do, which is show off a personality and generate chitchat.

Bilenko doesn’t expect this to change soon—at least, not in the next five years. The conversations humans have are “very difficult,” he said.