I've enjoyed lately re-reading your thoughts on clerics in D&D, particularly your blog post noting their relative absence in the Giants in the Earth articles from Dragon. To emphasize your point, consider clerics' relative absence even in Gods, Demigods & Heroes:
Nagas, Nike, Odin, Balder, Hel, the Maiden of Pohja, Ukko, Mitra, Asura, Pictish shamans, and priests of the Golden Peacock can use cleric spells. That's it. That's 7 deities, 1 monster, 1 hero, and 2 groups of Hyborean clerics.
The latter two groups are clearly given cleric powers in GDG&H only because they are priests, NOT because such powers are given them in REH's tales. (This is pretty much admitted in the entry for Pictish shamans, and I do not remember the Golden Peacock guys at all from REH's stories.)
Mitra and Asura are not depicted at all in REH's stories, but only mentioned. Why the authors gave them cleric spells is beyond me.
That leaves 2 figures from the Kalevala, 3 from Norse mythology, 1 from Greek mythology, and a monster from Indian mythology. I seem to remember Ukko being little more than a name in the Kalevala, and I certainly do not remember any clerical powers wielded in the Norse Eddas or in the Greek sources. I admit ignorance in the case of Indian mythology.
What we see here is that, not only in swords & sorcery literature, but also in mythology, clerics are mostly (if not totally) absent. One might be forgiven for thinking that clerics would be heavily present in a book entitled Gods, Demi-gods & Heroes, but this is certainly not the case. Compare the very frequent references in the book to the entities' fighting-man and magic-user abilities. These two are standard entries in the stat blocks! Hell, even psionics is a standard entry. But clerical abilities are not in the stat block.
Clerics really are the odd man out in D&D.
I (delta) think those are great points. I also think that many of us would perceive Sup-IV much more bluntly as a "super high-end Monster Manual", whereas that would get retconned or re-interpreted later as a series of of cosmic beings that you wouldn't ever fight. It casts a particularly harsh light (as if it was needed) on Gygax's pitch in the AD&D work that:
DEITIES & DEMIGODS is an indispensable part of the whole of AD&D. Do not fall into the error of regarding it as a supplement. It is integral to Dungeon Mastering a true AD&D campaign. Experienced players will immediately concur with this evaluation, for they already know how important alignment is, how necessary the deity is to the cleric, and how interaction of the various alignments depends upon the entities which lead them. [AD&D DDG]... when in actuality, the Cleric class is practically incompatible with the earlier source's work, as shown by Geof above. Other thoughts about that?