To break the whole industry into an analogy, I would say Atari made the paper, Nintendo made the envelope, Sega pushed down on the envelope, and Sony cloned the envelope down to the exact size, and shape, and got all the credit for making them.
Microsoft...well, they were licking Sony's envelopes, and got blisters, so they made their own.
I would say both Nintendo, and Sega made Gaming as it is today, and without them, Video gaming would of been a early 80's fad that died a quick death, and was not best remembered, like pogs and bucket hats, or Joe Bloggs Jumpers.