> seems to imply they have to pick and choose what they pursue. They really don't, especially if it's hard- vs software.

Money can often just be one part of the equation.

To do things well you also need - available & capable technical resource, suitable facilities, available & capable leadership and management (with engaging at the right level in the business) and a clear vision of what you're trying to achieve/working towards.

Given how Apple appears to operate, I wonder if a strong desire for senior management control/oversight over major developments means they (artificially) limit how many concurrent large-scale things they can work on at any given time?

Maybe not, but that'd be my guess.