While it sounds like a big upgrade over the current Xbox, HotHardware notes that Xbox Scorpio isn't expected to hit the market until late 2017. So while the Scorpio is on-par with a somewhat high-end PC today, that will no longer be the case when the console launches. NVIDIA's GeForce GTX 970 came out in September 2014 so the Scorpio will basically deliver 2014 high-end PC performance in 2017.
For starters, once new console hardware is introduced, it’s frozen for years at a time without any updates. So even if a truly kickass console powered its way onto the market, it would only be a short while before PCs would handily clobber it in performance. Secondly, Project Scorpio won’t be arriving until late 2017 at the earliest (barring any delays), so while 6 TFLOPs might sound good today, by this time next year the PC industry will be on a new cycle of high-end (and mid-range) GPUs with far superior performance.