Just to remind you of context, my experience is B2B SaaS at tech startups. These are relatively short turnaround cycles. Other types of businesses can have much longer cycles between engineers delivering a thing and other departments picking it up. But the core tension is the same.
If we don't know when the thing will ship, we don't know when other people's work kicks off. And we can't project what will happen with business metrics. That's why estimates matter.