the problem is that this assumes that estimates can be accurate, which in some projects may be the case, but in general there are always unexpected problems, things you didn't know you didn't know, etc.
If it happens that a company goes under because they lost all income because there was no deliverability, the problem was the company had the wrong team of engineers. Either too much "isolated geniuses" or too much inexperienced. Sometimes also happens that the management decides the way of doing work without technical involvement. Even companies I've been that decided to rewrite a mature and solid big piece of software, because they "needed to use more strategic technologies". Meaning, the technologies that were the "cool thing to use if you are a cool startup". And they use Agile (so they claim).
Here’s where I disagree and would say that a well-functioning process certainly can help with that, albeit not perfectly, of course. And that is by aiding the invididuals involved in interacting well.