I do not think its that weird... its not like you can vote on everything... the sypnosis seems catchy enough and its a new novel so people spend some time reading, check comments and see the vote thing in the sidebar and think, might aswell vote.
I doubt people spend an evening reading a novel and then go back to the power ranking or their library to click another novel and take special care to vote for a specific novel every day... I feel like the vote button is more used as a "like" button... people read something new, smack that vote button and because you do not have any more votes other novels drop in ranking untill you caught up to that latest chapter and the novel enters the back of your mind untill the next time you catch up... at least thats how it is for most binge readers.
So once the hype drops and the binge readers got their brainfood they will spend the votes on whatever they are reading next and the rankings will slowly sort themselves out... if you based power rankings on monthly votes instead of weekly I bet it would look totally different. It would at least drop a few ranks.