This is a topic which is extremely hard to cover and give a definitive answer using the historical method due to the nature of the country at hand and the time period. I believe, however, that the answer lies within the economics and politics of Yugoslavia.

Due to the extremely beneficial geo-political location of Yugoslavia, the USSR felt it necessary to attempt to "sway" them over to the Bloc, if you will. Stalin after the end of WWII was continuing his expansionism into Europe and knew that it might not take a great deal of effort to influence Yugoslavia, due to their already Far-left economy, towards the Cominform. However, with this period being the Cold-War, the US were right behind the USSR and knew exactly what they were doing. Due to the increasingly unstable economy of Yugoslavia, the US began pouring in military and economic aid to try to lift the burden. The USSR quickly followed suit so as to not allow the US any leverage over a country they felt was crucial in influencing the Mediterranean and the rest of Europe. This money would eventually become a main source of income for Tito and would fuel his arrogant ways within the economy of Yugoslavia. Tito, as the years passes, was growing ever-irresponsible with the management of the economy, with hyper-inflation and mass unemployment being some of the problems he failed to solve. The increasing amounts of foreign aid from both sides of the Cold-War allowed him to amass further debt. However, growth in the Yugoslav SFR meant that economic prosperity was seemingly around the corner to most foreign nations. Yugoslavia held the highest periods of growth in the world, which Mathematician David Schweickart maintains as he states "…the Yugoslav experiment in worker self-management sustained for three decades one of the highest rates of growth in the world [and] vastly improved the average standard of living”.

So to answer your question as to why they were able to do these things? It was due to world-wide economic support. The world believes that Yugoslavia could maintain their growth and would recover from their economic failings. Support from both the East and the West allowed for the continued IMF loans which could never be paid back, and would ultimately be a large factor within the breakup of Yugoslavia.