Most fans are designed to push a lot of CFM (cubic feet per minute).
Bit that is only good when there is no restriction.
When you need to push the air through a dust filter, throught a radiator, and throught the case and out the other side, all that produces a lot of friction and restriction slowing down that air flow.
GT fans have teally good static pressure. That's what you need when you try to blow that air throught a rad and other restrictions.
They have the best static pressure versus noise ratio.
You can't get a GT with LED's on it or any other fancy crap.
They were industrial fans that made it into the water cooling hobby because they are that good.
Nidec makes them. For industry. You can order them from Nidec if you want for about 6-7$ each. But you have to order about a 1000 of them.
So Scythe was marketing them for Nidec to cater to the WC hobbyists.
There is no point in using.a GT as a case fan, as they don't have a great CFM rating, but lots of static pressure, or inches of mercury.
Most fans are like a racing car, lots of CFM, or speed.
But the GT is more like a one ton pick up truck. More torque, or static pressure to push the air throught restriction like rads and dust filters.
I hope this answers your question.
You can get other fans that have more static pressure. But they do it at higher rpm, with more air noise, and more motor noise.