The sanctions from outside generally don't limit outside countries from providing aid, but the north korean government closing its borders clearly does. They've never allowed foreign aid workers in generally, and now they've evicted pretty much all foreigners. As the article says, they don't want anyone to understand how much better life is in other countries. Even when foreign countries attempt to send them aid materials no strings attached, the government typically stockpiles it for the benefit of those in power.

And yeah, the argument of "other people have it worse than you so you have no right to complain" is lazy self-serving garbage.