Although that sounds like a wise business decision, Hive account@wiser, there is the political hot potato issue of non-proof of brain voting in general. My feeling is a witness may value their record more than the short turn gains, by not taking advantage of such services but relying only on supporters' and steem cash flow projects like utility bots.

P.S. Imagine if delegating became an issue surrounding a fork vote in the future for example.

P.P.S. Self voting is another issue which may be best avoided for its short term gain, as well, for example.