Norman Winarsky was among those present at the birth of Siri, the voice-activated personal assistant that now lives in all of our iPhones. Initially a project of SRI International, Siri spun off as its own start-up and was acquired by Apple just two months after its launch in February 2010. (Winarsky headed SRI’s entrepreneurial arm at the time of Siri’s development and acquisition, and was a co-founder and board member of the original Siri company.)

In 2011, on the eve of Siri’s much-anticipated introduction on the iPhone 4S, Winarsky said he had no idea what Apple was planning to do with the technology he helped create. He did, however, “believe that Apple will use Siri to start another revolution.”

The revolution ended up a little clunkier than planned. Seven years after that launch, Siri still at times stumbles over spoken requests and struggles to integrate the many things it should know about you into useful responses. It remains the most popular AI assistant, but usage is declining. This isn’t where Winarsky thought Siri would be at this point. In a recent interview with Quartz, Winarsky said that the AI’s current capabilities fell short of his earlier predictions for the assistant in several key ways.

Siri is great for setting reminders, checking the weather, sending texts for you and other relatively mundane tasks. But it has an imperfect grasp of users’ preferences and past history. Its predictive intelligence is limited—it’s not great at knowing what you want before you know you want it. And while vastly improved from its earliest days, Siri still isn’t a sparkling conversationalist. “Surprise and delight is kind of missing right now,” said Winarsky, now a consultant and venture capitalist.

Winarsky acknowledges that some of this disappointment stems from the sheer difficulty of predicting the pace of major technological advancement, which Bill Gates once summed up as the human tendency to “overestimate the change that will occur in the next two years and underestimate the change that will occur in the next 10.”

But part of it is also likely because Apple chose to take Siri in a very different direction than the one its founders envisioned. Pre-Apple, Winarsky said, Siri was intended to launch specifically as a travel and entertainment concierge. Were you to arrive at an airport to discover a cancelled flight, for example, Siri would already be searching for an alternate route home by the time you pulled your phone from your pocket—and if none was available, would have a hotel room ready to book. It would have a smaller remit, but it would learn it flawlessly, and then gradually extend to related areas. Apple launched Siri as an assistant that can help you in all areas of your life, a bigger challenge that will inevitably take longer to perfect, Winarsky said. (It’s certainly not an impossible one—competitors like Google Assistant have already surpassed Siri’s ability to navigate travel and other logistics.)

“These are hard problems and when you’re a company dealing with up to a billion people, the problems get harder yet,” Winarsky said. “They’re probably looking for a level of perfection they can’t get.”