> The point of "defense-in-depth" is to add additional layers that mitigate different weaknesses. Maybe making a stronger layer isn't the same as adding an additional layer, but it has the same outcome, so it feels like a distinction without difference.

Not to speak for Filippo, but adding extra layers comes with a cost. Presumably they've weighed up the cost of adding this functionality (in terms of maintainer time etc.) and decided the cost of implementing it outweighed the benefit.