blower style fans are used so the Graphics cards can be used in very small cases with little cooling. All the hot air is expelled outside the case, NVidia does the same thing. And a little some thing the $1200 NVidia flagship reference card has problems with this cooling and according to some websites should have had water or a better cooling solution.
My old GTX 260 and my HD 6970 are blower style, but the HD 6970 was retrofitted with a 3rd party cooler
My GTX 660 To and HD 7870 both have factory dual fan coolers
You should look up undervolting GPU to get a stable but lower temp and power consumption of your GPU, generally look up on google if people found a stable value to stay at.
For instance the RX 470s by default may at most use 1.060v @1255mhz.
You can try tweaking the voltage down by -0.010 to 1.050v and such to see if your clocks remain stable with your games, and you can reduce temp of your gpu quite a bit.
I believe that on stock voltage, that same card can achieve about 1340mhz @ 1.06v, but this keeps your gpu at around 70 degrees Celcius or above.
If you don't mind using stock clocks you can undervolt the gpu and reduce temp and power drain.
EDIT: While dual fan gpu coolers help a lot, not everyone overclocks their GPUs with this, so the undervolting method can be helpful..
EDIT2: AMD reference cards are single fans for the reason of costs, if they integrated dual fan GPUs they'd have to make the price a bit higher, and the aftermarket gpu won't technically be that much cheaper.
While slightly more costly, dual fan coolers reduce RMA costs which mitigates the marginal cost of dual fans
I have had no problems with my dual fan cards, cannot say that for the EVGA GTX 260 SC which eventually overheated