Why it matters: To neutralize concerns about its market power, Facebook and other tech giants have to successfully define the markets they compete in as broad and teeming with other players ready to challenge their dominance.

What they're saying: During a recent House Judiciary Committee hearing on the market power of online platforms, Facebook head of global policy development Matt Perault pointed to TikTok as evidence that it's still possible to create a successful social network more than a decade after Facebook took off.

"We compete with companies from all around the world," he said. "TikTok, for example, a Chinese app launched less than 3 years ago, has been downloaded more than a billion times and was the most downloaded iOS app in 2018."

Rep. David Cicilline (D-R.I.), the chairman of the House Judiciary antitrust subcommittee, seemed concerned enough about Facebook's TikTok argument that he tried to dismiss it preemptively in his opening statement at the hearing.

He said that notwithstanding "the growing popularity of TikTok ... Facebook captures over 80% of global social media revenue."

Context:

TikTok, which is owned by Chinese company ByteDance, has seen its influence and user base grow substantially in the United States since it was introduced to a stateside audience via a rebrand of the lip-sync app Musical.ly.

Young people in particular have been drawn to the ability to share 15-second looping videos often riffing on established memes or popular sound clips. TikTok's appeal echoes that of Vine, the beloved video-sharing app shut down by Twitter in 2016.

The app has accumulated cultural capital as well. Lil Nas X's track "Old Town Road" saw its popularity surge earlier this year thanks in part to TikTok.

Facebook has, in fact, tried to copy the app's success with a similar product called Lasso.

Between the lines:

Unmentioned in Facebook's comments about TikTok is the fact that it not only competes with Facebook, but is one of its advertising customers as well.

A source familiar with the matter said that TikTok had spent substantially on online advertising to acquire new users late last year and early this year, including on Facebook.

TikTok does not release its user numbers, though in January one firm estimated that it was adding tens of millions of new users a month.

TikTok is not the only company Facebook cites as an important competitor. Others range from video sites like YouTube to messaging apps like Viber and Telegram.

The bottom line:

Facebook's TikTok argument is unlikely to placate its most fervent critics.

Asked last week about Facebook's argument around TikTok, presidential candidate Sen. Elizabeth Warren (D-Mass.) burst into laughter for 2 seconds, paused as we got onto an elevator, then laughed again.

She said that an argument like that coming from Facebook "is a reminder: These guys have too damn much power. It makes them arrogant and disconnected from reality, and I laughed out loud."