The "underlying issues" are things Uber management (1) understands better than outsiders looking in; (2) they're actively working to address; and (3) they have vastly-superior metrics to understand their own internal growth rate. They want to stay private precisely for this reason: They don't want to answer whiny questions from people who think they know better.
"Wildly overpriced" is speculative on your part (at best). This isn't a publicly traded stock. It's preferred stock, and valuation is ~1 line item in a contract that probably spans dozens of pages. Those other T&C's matter a lot: liquidation preference, participating preferred, etc. Those newest investors are certainly getting superior liquidation preference, and likely getting guaranteed ROI.
No - it's definitely not the 'same story' :)
The same was said about Google and FB, and Amazon - and they are doing very well.
It was said about Twitter and they are failing.
These companies are all quite different.
The underlying issues are the facts that need to be addressed.
X years ago, what was FB's user base, how much was it growing, could it be disrupted, and how much were they spending on ops/acquisitions ... and of course, how many $ could they squeeze out of each user are the fundamental questions.
The article is not unfair.
Uber is a great business that is probably wildly over-priced at this point.