Yeah actually i do. Most of my friends, and multiple guilds ive joined have bought gold. Ive seen gdkp leaders in discord directly linking gold selling websites, every week, and the same people are still doing it.
Gold buying wouldnt be as rampant as it is if people were actually afraid of being banned.
Also, gold buying is ONLY a 3 day ban and they remove all of your gold. Not a single person is getting banned for getting large sums of gold in gdkp, so im not sure why you think thats happening. Blizzard is not banning anybody participating in gdkps unless you bought the gold yourself. Look at how many people are on era right now with hundreds of thousands of gold