Why did Obama tolerate it?
Plausible deniability.
He can claim he didn’t know what Hillary was doing. Hillary was basically running a shadow govt without his knowledge and approval.
Shadow government -— after SHE was suppose to be the nominee and therefore the president. She’d show him! He couldn’t boss her.
Hard to claim he didn’t know anything about it when he was texting her on that account. But they’re above the law so what does it matter now?