They would much rather confidently repeat a date that is totally unfounded rubbish which will have to be rolled back later, because then they can blame the engineering team for not delivering to their estimate.
Having a promised date lets you keep the opportunity going and in some cases can even let you sign them there and then - you sign them under the condition that feature X will be in the app by date Y. That's waaaay better for business, even if it's tougher for engineers.
I’ve seen enough instances of work being done for a specific customer that doesn’t then result in the customer signing up (or - once they see they can postpone signing the big contract by continuing to ask for “just one more crucial feature”, they continue to do so) to ever fall for this again.