On paper, Thursday night’s “We, Robot” event may have belonged to Tesla’s robo-taxi, but the real star of the show was Optimus.

Elon Musk’s humanoid robot wowed attendees as a half-dozen or so navigated their way safely through the crowd at Warner Bros. studio lot in Hollywood entirely untethered.

Just two years ago, the droid couldn’t even make it onto a stage on its own. But the latest iteration was talking with guests, playing rock-paper-scissors. or simply pouring a drink from a tap for the thirsty—before coolly flashing a peace sign with its metallic hand.

“This will be the biggest product ever—of any kind,” Musk predicted on stage that night.

He wanted attendees to see the new and improved version of the robot for the first time, without relying on canned videos taken of the machine operating inside the walls of Tesla’s facilities.

“The Optimus robots will walk among you. Please be nice,” Musk added.

Not the first controversy for Optimus

While fans attending the event were duly impressed by the Cybercab and the larger Robovan—which was not preannounced—autonomous vehicles have been shown off before. Waymo even operates them commercially in select cities.

By comparison, nothing felt more futuristic than interacting with a creation known only from science fiction movies and books.

“Crazy, I’m talking to a robot,” said John Stringer, the founder of Tesla Owners Silicon Valley.

It was a stunning display of technological progress that transported attendees to the future, were it not for one thing: The machines were not in fact exhibiting any true artificial intelligence at all.

They were voiced and operated remotely by humans wearing special suits that translated their movements to the droid.

“Today I’m assisted by a human. I’m not yet fully autonomous,” one Optimus operator admitted on video that was shot by a guest who asked.

For many it was reminiscent of another controversy, when Musk shared in January footage of Optimus folding a shirt. Keen observers quickly pointed to the hand of its operator, which failed to be cropped out.

‘Call it the parlor trick it is’

Tesla has been training its robots with the help of people using specialized feedback suits, but Musk gave no indication on Thursday that the robots were operating by any other force than the AI with which they were trained.

He certainly did not mention that the ones in the crowd were essentially metal marionettes.

“Totally worthy to celebrate low latency remote control,” posted Josh Wolfe, cofounder of Lux Capital, “but totally dishonest to demo these as autonomous robots—call it the parlor trick it is.”

Neither Tesla nor Elon Musk responded to a Fortune request to explain their reasons.

Optimus is not just any prototype. Musk believes it will be Tesla’s most important product in history. In June, he predicted it would one day sell for as low as $20,000, cost half that to make, and sell 100 million times over every year.

Musk's $25 trillion business

As a result, he has gone on the record saying annual earnings from Optimus could hit $1 trillion. And if you add a multiple he estimates conservatively, that one business alone should be worth $25 trillion.

Omar Qazi, a veteran Tesla influencer with ties to Musk who functions like an unofficial brand ambassador, readily admitted humans were moving the robots like puppets, but he argued the prototype’s mechanics were still a major accomplishment, even if it lacked AI.

“If you’re not impressed with tele operated Optimus,” he wrote, “go try and make your own robot and try and make it walk through a crowded event without hurting anyone.”

But others, including Tesla content creator Jeremy Judkins, were disappointed by the lack of transparency. “I just wish Tesla was more open and honest at this event, because they gave no, no—NO—hints that the robots were controlled by humans,” he said.

This story was originally featured on Fortune.com