How far does it go? Are all bugs features? Shall we assume that Boeing (via MCAS) and Ford (via the Pinto) were trying to kill their passengers? There's a difference between ulterior motive and incompetent execution of expressed intention.
"People of the same trade seldom meet together, even for merriment and diversion, but the conversation ends in a conspiracy against the public." - Adam Smith
People do hide their intentions but that doesn’t give us a license to reduce complex system dynamics to absurdities.
Design features tend to persist.
The phrase/idiom "the purpose of a system is what it does" maps best to situations where a multiple decisions within a system make little sense when viewed through the lens of the stated purpose, but make perfect sense if the actual outcome is the desired one.
It is an invitation to analyze a system while suspending the assumption of good faith on the part of the implementors.
It’s not that simple. Especially not in politics but even in the domain you’re referencing, have you ever seen Mozilla’s bug tracker? Once your project is so big and involves so many people you move beyond fixing everything you want.
There may be central planning at play, in this case I assume there is, but to claim it necessarily is relies on an oversimplification that doesn’t exist in human political machines that are a giant ship of theseus essentially. There’s no identity -> management capacity proven anywhere enough to make that kind of claim. Institutions inherit and have emergent behavior driven by the dynamics of their constituents/individuals. That includes the inability to create imagined outcomes reliably. The platonic intent and physical regimes cannot be integrated.