People don't use weighted votes? I love them. I use them whenever I can. And push for them whenever I can too. Gives an incentive to lords to share a piece of their pie and to compete for knights.
You're talking about "representative" voting, where a lord votes for himself and all his knights. The OP is talking about the old weighted voting system, where different people get different numbers of votes, based on things like rank and prestige. i.e. a noble with 100 prestige gets 10 votes, but a noble with 10 prestige only gets 1 vote.
This is an unfortunate side-effect of the referendum system, where every nobles gets the same number of votes in non-representative elections. I'd like to see an option for prestige-related voting again. Perhaps only for certain government styles?