They sign big leases with big tenants before they can get financing, and the building needs to be open when the lease says it will.
Strangely enough, pretty much the last thing they do is to design the foundation. Once they know the building is a go, they drill and take core samples at dozens of places around the site and use that information to design a foundation that will hold the building as designed. This is the when things start to cost large amounts of real money, so they don’t do it until they have to.
The concrete mat that ties all the caissons together is a single pour that can involve hundreds of concrete trucks and take a day or more to do, all of it orchestrated to ensure every truck arrives exactly on schedule.
All this is to say that there is still an awful lot of skill in the construction industry.
And I'll note that the Empire State Building was not a standard office building of the day, but the tallest building in the world. (A title it held for 40 years.) People building today have an 80-year advantage, plus the rise of computers. You'd think we'd be able to do at least as well with every building, but we don't. That's in stark contrast to building safety, for example, where we're very good about learning lessons about keeping buildings from collapsing.
A talk that really opened my eyes was Mary Poppendieck's "Tyranny of the Plan": https://chrisgagne.com/1255/mary-poppendiecks-the-tyranny-of...
It turns out the Empire State Building was created on time and under budget, and against a very hard deadline. They did not have a complete plan when they started; they were designing the top floors as they were building the bottom ones.
In software, we've become familiar with how over-planning creates a lot of waste. But I was still surprised how broadly that lesson applies.