The few numbers that Uber posted look like good news for them, but let's not overstate things.
The reason that people post numbers YoY instead of QoQ most of the time is not to artificially inflate numbers. It's because lots of companies have yearly seasonality. If you looked at Apple's numbers for Q4 (real Q4, Oct-Dec, not Apple's fiscal Q4) quarter over quarter, they'd always look like they were on a massive, incredible growth trend. If you looked at their Q1 numbers quarter over quarter, they'd always look like they're shrinking.
Since Uber is sharing a very limited subset of numbers on a purely voluntary basis, it's pretty reasonable to assume that they're showing the ones that make them look good. If they wanted to show YoY numbers, they certainly could. It stands to reason that YoY numbers aren't going to make them look massively better than QoQ numbers.
And, finally, saying that you could "just" raise revenue by 6% and have it all go to the bottom line with no other effects is fantasy -- and even if they could do that, that would make them non-GAAP break-even, not "the kind of profitable company that justifies a $70B valuation."