I have no idea how this plays out in the US national lab system being discussed .. but a PhD is literally "my first independent solo original research project obsessed over and submitted to critical peer review".

It's the apprenticeship for doing independant solo research and, in general, makes perfect sense that someone have demonstrated a capability for this work prior to being given the reins to resources on the scale of millions, tens of millions, etc.

It's hardly a "glass ceiling" (ie. we profess equality but don't promote women or people of colour or not our religeon but never say why) when it's a stated requirement to, say, first pass an apprenticeship prior to becoming an certified electrician and hired to wire a nuclear weapon.

It's an actual formal staging in a meritocracy, the only issue would be if those that might gain a PhD are denied the opportunity to do so ... (a somewhat tangential issue that might have more play in various places).