Why not superpower countries just use nukes to win wars immediately?

There was an interview if I remember where the Saudi prince MBS said a country having nukes is actually a bane to themselves. Because they can never actually use nukes without becoming a pariah of the world so in the end, the nukes just become a 'deterrence' that's actually just costing the countries in the long-run for no real gain or benefit.

But I do question, what would happen if nukes DID become the norm in warfare instead? Just think about what if Russia just decides to nuke Ukraine to force them to surrender finally? Or US just nukes Iran to force a surrender? No matter how stubborn the opposing nation is, there is no way they cannot concede defeat if nukes start dropping.

If that becomes the norm, i think it could herald in a new age of military might where no amount of fighter jets or tanks a country has even matters any more. Or that matters is whichever country has nukes and can fire their nukes fastest.