OK, well look, I don’t know much, but this how I see the whole deal, As always, YMMV, so don’t be putting out any leg hold traps just because you don’t happen to agree.
The thing is, C. Mcvie’s very presence was predicated on a whole list of principles that, by the time the album had finally reached completion, had completely transmogrified or even vapourised, such that any possible rationale for most of her contribution had been rendered effectively moot.
When I was a young raccoon, plying my trade in an endless series of low rent dive bars and roadhouses, one of the many (outdated, yet ubiquitous) House Rules governing the conduct of the weekly booked C Grade bands that appeared was, that EACH member of the band was required to perform vocal duties on at least one song in the evening’s set list.
While the origins of this mandate were, presumably, to provide the most varied experience possible, in reality, what ended up, in every single instance, quite conversely, was that the bass player (the member most commonly resistant to vocal contribution), somewhere in the wilds of the second set, would mumble out a lifeless, dispirited, rote rendition of CCR’s already mundane “Lodi”.
Without fail.
I’m sure you can see where I’m going with this.
Irrespective of the sincerity and intended benefit of original motivation, the complete opposite of the desired result is often generated.
If one examines, pragmatically, the original reasons for C McVie’s presence on the roster, compared to the eventual outcome, it’s plain to see that there was no reasonable justification of any sort for her to be there.
ORIGINALLY:
She was the wife of the bass player.
She was the keyboard player
She was a hot (ish) blonde bird
She had a moderately compelling contralto
She filled out the background vox
BY RUMORS:
She was the wife of the bass player
She and J McVie were divorced and communications between them were at best strained
She was the keyboard player
L Buckingham was accomplished (and S Nicks was functional) on keyboards, and they ended up having numerous sidemen during touring to match the album sound anyway
She was a hot (ish) blonde bird
Nicks handily filled the blonde chick slot, and pretty much wiped the floor with her, in terms of attractiveness*
She had a moderately compelling contralto
Most of her meaningful vocals are doubled by Buckingham
She filled out the background vox
Between Nicks and, the aforementioned sidemen, a sufficiently rich BG vocal mix was easily achieved
Finally, any and all songwriting credits are dubious at best, first because of the exhaustive extent to which new songs evolved through the production process, and second and most significant, they were so totally and utterly blow-crazed throughout, The friggin Beatles could have showed up to sit in and nobody would have really noted it.
I hope this puts to rest a lot of the ongoing disagreement and contentiousness that have characterized discourse in this and other threads.
R
*It should be noted that, in subsequent years, McVie has actually matured into quite a fine looking woman, whilst Nicks’ pulchritude has dwindled considerably…last laugh and all that
:dance: 
