If a lot of people outside of your instance think you made a bad comment but few inside your instance do, limited downvote federation creates an inaccurate representation of what people think.
But we're cooler than anyone else. :P
It's much more important to me to know what kbin thinks about my comment, than it is to know what the aggregate of kbin+hexbear or kbin+lemmy.world thinks.
And if you do want to know you just hit view on original instance and see all the votes.