This is true. What i have noticed from my mining experiences is that the fans on the cards can be extremely suspect. I've had to buy quite a few AF cooling kits for my cards because the fans tend to get blown out. The chips themselves are fine...but those fans. Wobble Wobble Wobble! The MSI / XFX fans are the worst and i kept all fans at 75% max rotational speed.
I ran some benchmarks on my r9 280 as soon as I popped it in. I monitored the GPU temperature, but I never bothered to change the fan speed. Temperatures got up as high as 96 C GPU and 94 C memory. Afterwards, I changed fan speed to 100% and the temperatures barely broke 70 C. I looked at the card shortly afterwards and noticed that the blue sticker for my HIS IceQ video card had peeled off, presumably from the times in which I ran it at close to 100 C. I suppose sustained usage at those numbers can eventually break down the integrity of the plastic that is attached to the card.