That’s the wrong way to look at it. If HN struggles in certain situations then it is not right-sized. You don’t beg of users to walk an unintuitive happy path (i.e. logout when not commenting).
It is “right-sized” if it happens so rarely that it realistically causes no problems.
Rare is not never.
But never isn’t necessarily a reasonable goal. People will tolerate outages when it’s not lost money/business.
0: https://news.ycombinator.com/item?id=12911461