The analysis in the article is like looking at Tesla on an earnings per share basis, when it's actually heavily priced on forward projected earning potential.
Like Tesla, Tiktok is a growth stock. This valuation doesn't reflect its current value per user - it's baking in an implied doubling or trebling of its user base in some short time span.
I'm not saying that the assumption that Tiktok will meet its projections (and justify this valuation) is warranted, but I am saying that comparing Tiktok's $/user to Facebook, a mature/somewhat stagnant social network, is the wrong way to look at this.