Well, there's also the case where some internal engineering and product management think they have the right answer. But it may be a literally bet the company sort of thing. (Especially outside the software realm where once the bus has left the station it's not turning around.)

Now I know there are people here whose reaction is that executive management should just shut up and listen to what the worker bees say. But it actually doesn't seem unreasonable to me (and I've been on the product management end of things in a case like this) to have some outside perspective from some people who are mostly pretty smart to nod their heads and say this seems sensible.

As a bonus they create big spreadsheets that make the business planning types happy and keep them out from underfoot.