Being an economic powerhouse or not isn't required for the idea to be a reasonable and workable one.
But given the high levels of dysfunction/conflict that led to the breakup of the country, I doubt they'd meet whatever bar you set for "economic powerhouse".
The conflict was due to it being a federation of several culturally quite different nations. When Tito died, the politicians that replaced him started heavily pushing nationalist ideologies amidst the 1980s economic crisis (which was not limited to Yugoslavia).
PS. You're arguing with people who lived there. How can you be so certain you know better than those of us who saw it first hand? And I'm in no way saying it was a perfect system, btw.
If you had lived in then you should know the standard of living was poor. More then a million people left to work in Germany as Gastarbeiters to send money home. Gas was limited. Common goods had to be brought through the border with Austria or Italy. Inflation was crazy, everybody bought German Marks the same day they got their paychecks, otherwise the money was worthless by the next day. What happened to you if you were caught as a political opposition in Yugoslavia is a story on its own.
But given the high levels of dysfunction/conflict that led to the breakup of the country, I doubt they'd meet whatever bar you set for "economic powerhouse".