Sadly for Afghanis, I doubt they could actually use their passport to travel to the countries that freely admit them. Many of those countries are very remote and impossible to travel to without stopping in another country first.
Lots of countries offer visa free transit though, right? You usually don't need to even go through customs when getting a connection international flight.
Even where you usually stay in transit area, the country may demand transit visa for certain passports (such as those on top of this quiz), which means the airline wouldn't allow you on the flight for starters.
You can follow the link at the top of the quiz, then select "Compare", and you can find out which countries work for North Koreans. (For example, Tuvalu!)
Armenia, Bangladesh, Belarus, Bolivia, Cambodia, Cape Verde, Comoros, Ivory Coast, Cuba, Djibouti, Dominica, Ethiopia, Gabon, Guinea, Guinea-Bissau, Guyana, Haiti, Iran, Jordan, Kyrgyzstan, Laos, Lesotho, Macao, Madagascar, Malawi, Mauritania, Micronesia, Mozambique, Myanmar, Nepal, Nicaragua, Nigeria, Palau, Palestine, Qatar, Rwanda, Samoa, Senegal, Seychelles, Sri Lanka, St. Vincent, Suriname, Tanzania, East Timor, Togo, Tuvalu, Uganda according to the source, but I know a lot of people will go to China visa free and South Korea of course does not require a visa.