The blockchain doesn't lie. Just check out this account: stembot. The account was created and powered up to the tune of 40000 steem power. The account was then used to go around flagging other people with the intent of driving them off of steemit. Why would he try to hide this by using an alt account instead of his own? Do you really want a top 20 witness who does this sort of thing? Even going as far as attacking another witness.
This kind of thing is why everyone I came to steemit with have left. They were driven off by the flagging, circle jerk voting, and vote buying.