Ethnic tension was always there, especially in regions such as north eastern Bosnia where they was, and still is, large populations of ethnic Serbs, who didn’t want to be part of an independent Bosnia.
To say that individual republics were stupid to vote for independence because of what happened in Bosnia is ridiculous. Were Slovenians wrong to vote for independence in '91 because of what happened in Kosovo in '99? Of course not.
You think those ethnic tensions that go back hundreds of years would have been supressed had Belgrade retained its control over all of the republics. No, and it could be argued that the war, that was largely confined to Bosnia, would have been far more widespread had Belgrade not allowed independence votes in Slovenia, Croatia, Montenegro etc
I’m done. Seriously, read up on it. It’s far more nuanced than you’re portraying it.