One look at the CS forums says this is wrong. Do some research on this and you will see there are people receiving varying types of account action for purchasing gold. It is also all over reddit.
Is just one, typically these threads devolve and are deleted. However to say nobody is being banned for this is patently and provably false.
Report them for it. They will be actioned.
Discord interactions are not under Blizzards control.
Sometimes. Infractions are cumulative.
Also wrong. Can be proven by spending a short time looking into it on the CS forums.
I get you and others dislike RMT, I myself am not a fan of it or GDKP, however there are actions being taken. We just do not see them as is the industry standard.