Even in this article, WeWork’s $7.8bn expected valuation is quoted unadorned. It’s a number that was derived by the same people and processes as the $47bn, yet one is ridiculed and the other presented as fact.
Startups don't really have valuations like a public company. You don't have anywhere near the same liquidation preferences in public companies as you do with startups. I'm pretty sure the bankruptcy protections aren't as good either.
And people keep making these valuation comparisons anyway. Probably because even in finance you can get loans and whatnot as if the valuations are the same.
Valuing complicated capital structures is well studied. (Many public companies have complicated cap structures.)
The wrong way to do it is take the top-of-the-stack share price, multiply it by everything outstanding, ignore debt, and equate it to enterprise value. That number means something, but the obsession with it in the Valley incentivised Vision Fund-style antics.
Usually stories did mention their mounting losses and relatively small revenue, once that info became available.