I'm trying to have a logical discussion
Likewise.
"High-level spells must all cause only light wounds because they can all be rectified by multiple castings of 'Cure Light Wounds?'" Really? Spell name semantics -- that's the position you're taking?
Because I don't know what range of games you've played and/or are familiar with, I don't know what expectations and assumptions you are bringing to this issue.
But for me, what you calll "spell name semantics" is actually very important.
In the real world, for instance, injury - especially modest injury - generally isn't cumulative. For instance, if I cut my thumb and sprain my ankle, the two can heal simultaneously; and progress in the healing of one (eg visiting the physio for my ankle) is pretty irrelevant to the healing of the other, and vice versa (eg visiting the doctor to get my thumb stitched up).
But hit points are strictly cumulative, and can be restored either in big chunks ("Cure Critical Wounds") or in modest little chunks a bit at a time ("Cure Light Wounds"). What, in the fiction, is all this meant to represent? Upthread, you suggested that in the case of Disintegrate it's destroyed skin, bone and/or muscle. But I can't see that.
For instance, a PC falls 10' and takes (pre-4e) 1d6 hp of damage - lets call it 3 hp. S/he has (let's say) 5 of 8 hp left. What does that hp loss represent? Probably not a sprained or broken ankle, because s/he can still walk and run normally. So let's say its bruising and cracked ribs.
A Cure Light Wounds spell (for 1d6+1 in B/X, or 1d8 in AD&D) is just right to heal this injury, which seems aptly described as a "light wound." But how does magic which restores bruises or mends cracked ribs help when what has happened is that your skin has been eaten away and your bone and/or muscle destroyed?
Now put in the other point to which I referred upthread - that the 11th level victim of a Disintegrate spell can still probably wrestle and defeat a tiger bare-handed - and I find it even less plausible that a Disintegrate spell has destroyed any significant quantity of skin, bone or muscle.
The contrast with a system like Rolemaster or HARP is, for me, very marked. In those systems, hits from weapons either cause bruising, bleeding, pain and fatigue ("concussion hits" is the technical term), or cause particular defined injuries ("criticals" is the technical term). Lose enough concussion hits and you suffer penalties to action, or eventually fall unconscious; take a critical and you suffer penalties to action, lose the use of a limb, or perhaps are dismembered or disembowelled or decapitated. (Or in the case of a 00 "E" Electricity critical, "foe returns to the dust from which s/he came.")
And the healing system reflects this. Recovering from a broken limb takes weeks. And happens in parallel with recovering from other injuries. And healing spells are ranked in power. Regrowing a limb requires more powerful magic than healing a fracture. Which requires more powerful magic than healing a bruise.
The system isn't perfect. It has oddities, and the healing magic and injury system aren't fully synchronised in the descriptions and categories that they use. Still, it makes it pretty easy to envisage what is happening in the fiction when someone gets hurt; and what is happening in the fiction if they heal by resting, or if they are healed by magic.
This is a system in which a Disintegrate spell can strip away skin and rupture bones and muscles, and the mechanics give effect to that. (One of my players once played a destruction mage, called a Sorcerer in RM parlance.)
Whereas in D&D, that interpretation of the spell just makes no sense to me - there is literally no point at which the mechanical resolution of the spell or its consequences is consistent with such fiction. Either the target of the spell suffered no serious harm (but simply the stress of fighting off the magic), or the target was turned to dust. Introducing the warlord into this situation then makes no difference - a warlord can't help anyone who's been turned to dust, and a warlord's inspiration very obviously can help someone recover or push through the stress of fighting off magic.