I think I already answered this but I'll put it a different way: (1) not as easy as it sounds; (2) it would be easy to tell that they were doing it; (3) if they do it, we'll improve the software so they can't; (4) if that doesn't work, it's a minor feature and we can easily drop it.
How easy it would be for bad actors brigading with freshly created accounts, or not-so-freshly created accounts with a history of brigading, to abuse this feature to censor stories?