Story highlights Former Google+ employee says the social tool has failed

Hashtag inventor Chris Messina left Google over a year ago

He says G+ could have been about identity, became "Facebook lite"

A former Google+ employee who spent three years helping create Google+ has written a brutal blog post declaring the tech giant's social network a failure.

In a lengthy, at times profane breakdown on blogging platform Medium , Chris Messina, the man credited as inventor of the hashtag , writes that Google missed a chance to make the service a one-stop home for its users' online identities and, instead, created a less-popular Facebook copycat.

"Lately, I just feel like Google+ is confused and adrift at sea," Messina wrote. "It's so far behind, how can it possibly catch up?"

The November 28 post was a follow-up to a tweet in which he had mistakenly called out a bug on Google+ that was actually caused by an external app. Even as he corrected himself, he called out Google for the network's missed opportunity.

"I f---ed up," Messina wrote. "So has Google."

JUST WATCHED Inside Google's billion dollar airfield Replay More Videos ... MUST WATCH Inside Google's billion dollar airfield 00:56

JUST WATCHED Europe piles pressure on Google Replay More Videos ... MUST WATCH Europe piles pressure on Google 02:34

JUST WATCHED Google enters space race Replay More Videos ... MUST WATCH Google enters space race 02:40

JUST WATCHED Google boss talks power of innovation Replay More Videos ... MUST WATCH Google boss talks power of innovation 03:58

Messina left Google over a year ago to join a startup. Before that, he had worked on the short-lived Google Buzz social product, then Google+.

He wrote that while it was being developed under the code name "Emerald Sea," Google+ was internally being called "Google Me." The idea at the time, he said, was to make the site a sort of home base for users, where they would decide which information they'd like to share about themselves and with whom they'd like to share it.

"It was like Google was saying, 'We're going to be your trusted partner in cyberspace, and we'll help you surface the right information to the people you choose, at the right time'," Messina wrote. "It was a functional search-oriented value proposition, rather than a social networking one.

"Thus, for me, when I searched for my mom's phone number on Google, I actually find it -- because it would be on her profile and she would have shared it with me. Suddenly a query like 'mom phone number' would work."

Instead, he wrote, Google+ became "a kind of Facebook-lite."

"Why did the world need another Facebook, unless to benefit Google by making their ad targeting more effective?" Messina wrote.

Google did not immediately respond to a message seeking comment for this article.

Messina wrote that innovation appears to be slowing for the Web tool. In a chart, he said Google+ and Hangouts, its well-liked video chat tool, have been updated with six apps each in 2014, compared with 15 for YouTube and 16 for Chrome, both of which are also Google properties, and 19 for Facebook, 29 for Instagram and 33 for Twitter.

Aside from his personal interest, Messina said he's disappointed because Facebook, with its more than 1.3 billion users, needs competition.

"The future of digital identity should not be determined by one company (namely, Facebook)," he said. "I still believe that competition in this space is better for consumers, for startups, and for the industry. And Google still remains one of the few companies (besides Apple, perhaps) that stands a chance to take on Facebook in this arena -- but Google+, as I see it, has lost its way."