It's a matter of perspective I guess, but generally having your competitor fumble out of the gate shouldn't diminish your achievement if you do a nearly perfect run I think.
People should also admit that Sony read their userbase and the market expertly, made the right calls pretty much all along (including when unseen circumstances such as delays and technical problems arose, cf Driveclub/ UC4/ R&C...) and had to rely mostly on third party for 2015.
"A" factor for the PS4's success was certainly MS botching their launch, no doubt. But even if it was a big one I doubt it still explains this global domination when within 6 months MS had 180'd most problems and launched programs to try one'uping Sony everywhere they could.
It's also frankly a very American PoV, when it's actually Sony building their brand, presence and support internationally that explains the WW ratio mostly imo.
In the US, they positionned their messaging "for the gamers" with a mix of relatively powerful hardware architecture, no Drm messaging, Gaming identity and marketing savyness (which is sort of new imo, for SCEA at least).
The biggest mistake Sony made in the US imo was a very limited run of the GTA bundle at $349 in 2014. But again, they made more money (less sales), and now we're up to 1.32m gap at the end of December in the US alone.
