Also milking and SPAM already happens

Milking and spam is somewhat contained by the superlinear (at the low end) curve and dust threshold (another form of low-end supearlinear) which makes it not very profitable, if at all, to split up votes across a large number of small payouts that both bloat the blockchain and require a huge amount of effort for anyone to find, examine, and possibly downvote. Without that property, the problem gets much worse, which we already saw to some extent with linear. Going to sublinear would make it catastrophic. Death by a thousand (or a million) cuts.