Yugoslavia no longer exists.
While Serbia may be -- I've been there twice and it's a rather scary country -- the other fragments of Yugoslavia are far less so. Bosnia has a distinct Ottoman influence, while Croatia and Slovenia are very Western Europeanised indeed.
I haven't been to Montenegro yet, but had the best beer I tasted in Bosnia was Montenegrin (as opposed to the awful Jelen).
So, no: only one of its fragments, I think.
What was scary in Serbia? And I agree, Jelen is bottom of the barrel. Only worse than thet would be private store brands, and you might even find better than Jelen among them.
The T-shirts on sale were another example. My Cyrillic is poor and my Czech is too but I can understand a bit. One was in English: "I am Vladimir Putin, and what I put in, stays there." The ones praising "war heroes" were worrying, too.
On my train back to Budapest the last time I was there, the crop-haired older gentleman opposite me was reading "Ветеран" magazine and a biography of a general.
The general impression I got was that here was a country whose sympathies lie East, not West.
At the time, I lived in Czechia, and I drove to Guča with some friends. The cultural difference from where I lived and where we drove in a single day -- and we didn't drive fast -- was shocking.
On my next visit, I had an overnight stop.