Partialy you have right.
If you do extreme programming, it may be true at beginning.
In most cases of game devel there are developer co. and publisher co (means producer). Publisher pays for developing game. To do that, they must sign agreement. To sign it, developer must prepare work-schedule to make possible calculate costs. Without it, none of Publishers/producers will make a deal.
Believe me, with some skills it is not too complicated to predict time of developing. Whole work you may just split into stages and evaluate those costs. It is also possible to over-estimate costs in case of expecting problems. With those information dev co. is able to paralelize work, hiring programmers etc. Without it it is impossible to do it effectively.
Finally ISI doesn't do that from scratch. They have basis, that have skills. I'm sure they don't do that ad-hoc.
Only exception is that ISI develops and publish things. So they not dependent on some signed deals.