The premoves are useful at least for forced recaptures. You can premove a move that's illegal at the moment, for example after 1.e4 e5 2.Nf3 d6 Black can premove ...d6xe5 that will be played immediately in case of 3.Nxe5. More useful examples are when a knight is pinned and you play h3/h6 and you think the opponent will take.
Otherwise, thinking your opponent can hack chess.com servers or at least the channel that calculates lag comensation and so on sounds a bit paranoid, doesn't it ?
EDIT : read your link. This is paranoia from the OP. #20 should convince you chess.com knows what they are doing.
Hi Frank124c,
This is the article I told. Just read it then you know.
http://www.chess.com/forum/view/community/clock-hacking?page=1
Thanks
KSBK