Sue,
If you're referring to what I wrote, did you actually read what I wrote?
You talk of "over", I was speaking in terms of "under".
Progress was also a homogenization of the 48 constellations to the Middle Way of 12 ... way back when.
There are groupings of constellations both above and below the Middle Way (ecliptic).
Therefore, in view of "progress" who's not to say as the field of discovery (and rediscovery) broadens, so do the stars/constellations in astrological use?
Not really a step forwards, it's probably more of a step back to the originals charted - but would involve knowledge of such, and a broadening of current perspective.
These newly appointed sub-leaders may conceivably have greater significance in constellations further north or south of ecliptic which, due to centralized focus on ecliptic, get homogenized back as sub-territorial rulers along the Middle Way.
Imo, Pluto has not usurped Mars rulership of Scorpio, it simply added a new dimension. If starting at Pluto for an understanding of Scorpio then it leads towards Mars, Sun & Moon.
Insofar as cycles of Pluto in relation to nativity - someone does not have to live a full orbit of Pluto to personally experience its effects at any given point in time. Cycles of time unfold - the totality of the orbit does not exclude the cross-quarter periods etc.
And the nature of it's orbit is a dividing point between planets orbiting either side.
One of the basic tools of astrology is translation of light, and Pluto is a physical object capable of translating light with faster moving planets collecting it, modifying it, and passing it along ... all the way back to earth.
No astrological authority has yet granted Ceres rulership "over" Virgo, ruled by Mercury. This smacks of hysteria - Ceres was discovered conjunct Algol.
However, who's to say it doesn't work under Mercury, ruler of this nocturnal southern sign? Conceivably, governing a constellation further south of Virgo who's qualities have been homogenized back into Virgo.
Over/under is a matter of perspective. Ceres was Spica (of Virgo). Does a Fixed Star prevail over a wandering one? Or do the wandering ones prevail because of their proximity to earth, translating light from those objects further away?
"Isn't this perhaps allowing a bunch of astronomers to determine what is and isn't significant in the philosophy of astrology rather than astrologers?"
How do you arrive at that? Astrology is reliant upon astronomy - it was the study of the stars in relation to earth that gave rise to interpretation in the first place.
The two work hand-in-hand.
Simply because people struggle with ordering and interpreting chaos does not diminish the significance of astronomical discoveries, either now or way back when...
Sure, it's important to start with the foundations ... a little problematic as the "foundations" are still being discovered and translated.
TS