they havent. Profile are still up, they have not been banned and some of them server transfered and locked their profile on raider.io and wowprogress.com
You can check xerwo from echo on twitter amongst others. Apparently some stuff with torghast. But ye, they either get their accounts deleted or in the very least a very very very lengthy suspension.
They would get their accounts banned regardless of whether Echo noticed. Blizzard monitor the RWF & would notice a bunch of scrubs suddenly getting Mythic kills.
Not necessarily. They pay attention to the race yes, but as long as guilds dont pop up in the halls all of a sudden its possible it flies under their radar. Their issue was that they got tracked by multiple third party websites which then attracted attention. They also tried to remove themselves from said websites by going private after people noticed and posted about it. Alas too late as it seems.