Your example creates an asymmetry where there isn't necessarily one. To make the situations comparable, if you're adding something, you should have to convince

Your example creates an asymmetry where there isn't necessarily one. To make the situations comparable, if you're adding something, you should have to convince the N people that there are no better things to add. The same as your suggestion that they would need to accept that the removal of a particular thing is preferable to all other possible things that could be removed. In fact, it seems easier to remove something since there are only the things that people have already agreed on. To add something it could be compared to a world of possibilities which might be better.