OK, so the scenarios you're talking about, perhaps it's something like what's going on with the bass in Deacon Blues?
The verses start off really grounded with the bass playing the lowest note of the keyboardist's chord voicing, for the most part.
Then, those grounded 8 bars are followed by 8 bars that aren't so weighty and grounded, and in those sections, I think Rainey is playing extension-function bass notes (2/9?) rather than reinforcing the harmonic floor, which seems to compliment what that section is trying to achieve.
(EDIT: I shortened and cleaned-up some of the logic in the section below, based on findings later in the thread, for the sake of the 1-2 humans that may stumble over this bit in the decades ahead.)
The chords in this less-weighty section are complete as-is, and the bass isn't necessarily defining the harmony here. Rainey sticks to just playing the one note that is (presumably) defined in the chart, not a root5 pattern -- he doesn't deviate from the anchor tone until he's transitioning into the next chord. In a situation like this, I'm not sure he'd have a lot of freedom to play anything more than just the one note in the chart. Among other concerns, he's gotta preserve uncertain/questioning vibe in those 8 bars, making each return of those grounded sections feel that much more peanut-butter in the contrast.
This is where I'm currently at/struggling in my learning. I'm trying to figure out what kind of freedom/good-choices a bassist has in all these different slash chord scenarios... do these sections in Deacon Blue demand that the bassist keep things pretty conservative, or are there equally-viable options that I just don't see yet? (probably the later).
Then there is Babylon Sisters, where Chuck seems to be establishing root notes that are NOT in the chord voicings floating above... and so he's playing a root/5th pattern throughout the verse sections, presumably to define a harmony that wouldn't otherwise be there.
In Babylon Sisters, Chuck's playing seems to be treating the chords voiced by the keyboard as upper structure/color. Is Chuck doing exactly the opposite of what Chris is trying to do in these Dog & Pony tracks? Chuck is hitting those 5ths to pull the harmonic center of gravity away from the keyboard parts, and Chris is avoiding 5ths to avoid shifting gravity in that same way.
Also: "Cenotaur" sounds like a line of vitamin gummies at GNC that are laced with male-enhancement ingredients.