The thing is Nvidia drop the balls just as much, such as the drivers in the recent years, but it doesn't stop people keep thinking they are doing better than AMD in that regard, and that's what the bias are...
The "overclocker's dream" we all know it was a slip of mouth by the AMD representative, but at least it was not listed as a feature on the box of the product. The 4GB of the 970 on the other hand...Nvidia claims the card was meant to be 3GB, and the extra 1GB is just their "genious gift" to their users due to how "they are always looking out for their users"

(So should performance suffer with the card accessing the last part of the 1GB of vram, users shouldn't complain

)
The only reason that AMD appears to drop the ball more than Nvidia is only due to Nvidia's better branding image, so even if both companies have the same amount of smudge stucked on their faces, the smudge would simply disappear from Nvidia's face at a much faster rate