The article only cited the two parts that had the most to lose from the breakup.
The Serbs, that missed their pseudo empire, and the Bosnians, that missed the suppression of ethnic tensions.
Croatia, Slovenia, Kosovo, and Montenegro (whom held on the longest), seem to be happy with the current situation.
I don’t agree with you. Serbia was the largest of the countries that made up Yugoslavia and Kosovo was an integral part until after WWII when Tito actively removed Serbs from the area and allowed mass migration of Albanians into the area in order to water down the Serbian identity within the country. Then he created “autonomous provinces” out of Kosovo and Vojvodina, both parts of pre-Yugoslavia to further weaken the Serbian identity. Tito did similar things in the other parts of the country but none of the other areas had large swaths pulled out and made “autonomous”. Kosovo is the historic home of the Serbs and the center of their medieval history so that was an obvious place for Tito to target by Albanizing it under a greater Yugoslav identity.
Serbs were asked to give up their identity on a much larger scale than any of the other groups and sacrificed the most people (they were the largest part of the population) in WWII for the country of Yugoslavia. As such, it’s not surprising that there’s some nostalgia for the country given the amount they sacrificed to create it. Remember, at the origin of Yugoslavia, Croatia, Slovenia and Montenegro all asked the join Serbia in creating Yugoslavia. Serbia did not ask those countries to join it in creating that country.