Yes, but there had been intellectuals from all South Slav nations, who were in favour of creating a confederation of all South Slavs.
Among them were the proponents of the „Greater Serbia“ idea, but others envisioned a country in which political power would be equitably shared. A few even advocated rights for the non-Slav minority populations…
True there were some....but they were never a majority or even close to it. They theorized of some south slav union which sounded good to them but as soon as Yugoslavia was put together and it became pretty clear that it was Serb dominated, pretty much all of them immediately hated that and since the Serbs weren't numerous or strong enough to impose their will effectively, Yugoslavia immediately became riven with internal strife.
Interestingly Tito managed the delicate juggling act pretty effectively but he was not a Serb nationalist. He was a Croat/Slovene himself.