For a great many software projects no formal spec exists. The code is the spec, and it gets modified constantly based on user feedback and other requirements that often appear out of nowhere. For many projects, maybe ~80% of the thinking about how the software should work happens after some version of the software exists and is being used to do meaningful work.
Put another way, if you don't know what correct is before you start working then no tradeoff exists.
> Put another way, if you don't know what correct is before you start working then no tradeoff exists.
This goes out the window the first time you get real users, though. Hyrum's Law bites people all the time.
"What sorts of things can you build if you don't have long-term sneaky contracts and dependencies" is a really interesting question and has a HUGE pool of answers that used to be not worth the effort. But it's largely a different pool of software than the ones people get paid for today.