I think there's some truth to it. Slovenia was always Western and trade orientated, even during Tito's era. I don't remember the year, but I saw one figure that suggested that their GDP was around 184% of the national average, and that the average would have been even lower if it wasn't for the strategic decision to locate a significant amount of defence industries in SR Bosnia-Hercegovina. Croatia on the other hand was gaining huge amounts of cash from tourism, and both of them heavily resented the fiscal transfers to places like Kosovo, especially as the cash was mostly wasted on vanity projects.
Serbia in particular was in trouble when both Slovenia and Croatia made it clear that they were going to withhold transfers to the central government in Belgrade unless there was meaningful reform of the state, and I'd argue (backed up by what the JNA was actually doing in 1990/1991) that the plan of the Serbian leadership was to use the Serb domination of the army to reform Yugoslavia as a centralist state. The Army enjoyed almost mythical status in Yugoslavia, and it was obvious that they were very unhappy about the democratisation of Yugoslavia, as it was always going to lead to a loss in their position. It's backed up by the way that Slovenia and Croatia both established parallel military structures in 1990, and also in the way that Serbia took much longer to hold "democratic" elections in 1990, which were the only republic-level elections to be won by the Communists (masquerading as if I remember correctly.
It's worth pointing out that in both Croatia and Serbia, political cronies seized huge parts of the economy for themselves. Croatia had one of the most unbelievably corrupt privatisation processes, and Serbian businesses were wrecked by them being used to fund Milosevic's games. So, for sure, they were using ethnic politics to seize control - in different ways, but still the same thing.
I do think Yugoslavia could have been saved, but with both Tudjman and Milosevic using nationalism to cover up their games, it was a lost cause. The West does deserve some blame for fanning the flames though, particularly with the recognition of Croatian independence through the stubborn insistence of Germany when other EEC countries were hesitant. I think there was a general attitude on the part of the EEC that Yugoslavia could be encouraged to stay together with the carrot of EEC membership dangling in front of them, but that it was wrecked by the German push to recognise Croatia.
What could have been done differently? It's hard to say, because Yugoslavia was in such a financial mess that it was going to be nearly impossible to get out of it with the structure that they had.