1) GTX 1070 has a rating of 6.5 tf. The reason Nvidia performed better is that most games are based on the crappy dx11 and Nvidia used fp32 and AMD for fp64 for high quality rendering, which despite lower fps, amd is both less laggy an looks better on the same setting. If you compare g sync and freesync enabled graphic on same tier cards you will see the difference. However this strategy is more suited towards mobile.Also, there are 2 things that bring the Switch closer to the XB1/PS4 real-life-performance.
1st: Nvidia's GFLOPS are almost always better than AMD's. AMD has a card with 4.8 TFLOPS (RX 480), but Nvidia's 4.8 TFLOPS card (GTX 1070) is 50-70% faster.
2nd: The OS is more optimized for gaming.
Xbox has parts of Windows and PS4 is FreeBSD based, while Nintendo's OS is purely made for their own hardware.
//Sent from my glorious OnePlus X
2) Most non-microsoft systems are at least somewhat linux.