That was (mostly) a peaceful split, with countries that had been dominated by the Soviets for 50 years gaining independence. The rest of the Russian empire has been under Moscow/St Petersburg for 500 years. The ethnic Russian elites will not give up their Asian territories without a fight.

And, after what's happened to Ukraine, none of the new states will give up their nukes. We'll have a nuclear armed Dagestan, run by whoever was aggressive enough to seize power.

This is what is called over-updating on a single event. Probably the key difference is that each soviet republic was already a discrete identity based on ethnic, cultural, and historic ties, and so the default was simply to revert to that identity. For a state with no clear discrete sub-identities, nor with enough economic or military autonomy to survive as an independent state, civil war becomes much more likely as these lines are forcibly drawn.