This is not entirely true. There are plenty of people of that opinion but there were plenty of people that thought that the US would be able to achieve air supremacy, and then destroy the missile cities, which would eventually mean Iran would lose its ability to close the strait and attack US bases and the Gulf states in a matter of weeks and months. Those people were wrong, and the US failed to achieve these tactical goals against a conventional military power, which is not something many US strategists were used to.

Of course plenty of people expected it would happen the way it did, but it was not unanimous at all. I have no doubt many in the general staff were rudely surprised.