One thing that interested me about D&D 3.0/3.5 was the idea that characters of a certain level were assumed to have X magic items or Y value of mundane items. More or less than that, and you'd know they were better or worse equipped than other characters of the same level. Further, the overall effective level of the character was known, even for multi-classed PCs, and encounters in published adventures pretty much scaled to them.
But that idea didn't start wholesale in D&D 3.0/3.5. It existed in some form in 1st edition AD&D.
I was re-reading S4 The Lost Caverns of Tsojcanth (brown cover, 1982 edition) and it contains a passage about the relative level equivalencies of the party (pg. 3, under "Adventuring Characters.") Summing up, the adventurers should be 6-10th level, and if there are more than 4 9-10th level guys the monsters should be beefed up. Double-classed PCs are considered to be the average of both classes, plus two (or plus three over the highest level if one class is much higher level than the other). Triple-classed are highest level plus four. So the adventure is meant to be scaled, if you're too high level for it - something I've heard was not done in Gary Gygax's own Greyhawk campaign a decade earlier. This is admitted a published, converted tournament adventure and not a long-running game, but it's interesting to note that scaling/appropriate challenge came along at least 30 years ago.
That's level and encounters. How about magic items?
Further down, under "For the Dungeon Master" is the following passage.
"(If the party is relatively weak in levels, numbers, or magic, use Appendix C of the Dungeon Masters Guide (Party Magic Items, pp 175-76) to equip the part with magical items appropriate to their levels, to bring them up to strength."
I can't help but think you're supposed to determine their "relative weakness" by looking at the section above, the pre-gens, and very likely pp 175-76 as well.
This isn't the only 1st edition, Gygax-era AD&D module to offer up fairly specific advice about what the party should have or consist of to survive the adventure. D1-2 and D3 stick out in my mind, and I'm sure there must be others. But it stuck out to me as an example of connecting to a level-appropriate amount and quality of magic items. Further, it ties it to one of three existing subsystems for determining what a 1st-or-higher-level character "should" have. One is the aforementioned system for NPC parties. The other is at the end of Appendix C, page 194, and the other is all of Appendix P, starting on pg. 225 (which, as an aside, prescribes 4d-drop-lowest for stats).
Each of those systems varies a bit:
- page 175-176 hands out some items automatically, randomly rolled from tables, and others on a percent chance of a table roll. Tables are more-or-less by power level.
- page 194 splits it out by item with a percent chance per level of having a magic item, but no details on how powerful or where to roll except for a single table on protective devices (rings, cloaks, bracers, etc.).
- Appendix P assigns percentages to type and quality of magic armor, scrolls, weapons, and potions. The player gets some input here, picking where to make their percentage rolls (opting for higher chances for a certain items, such as magic chain armor instead of plate, or a sword instead of a bow). Miscellaneous items are handed out to the group as a whole.
Each of these systems give pretty divergent results, and have different aims. Appendix P especially stands out (and IIRC it first showed up in an early issue of The Dragon) as it's meant for generating higher level PCs for a pickup game, especially for conventions.
I thought it was really interesting to see one of these systems picked out as a way to beef up characters who didn't quite have "magical items appropriate to their levels." That's not something I've heard much about with regards to early edition D&D, but systems for it already existed by the time I entered the hobby in 1981.
In some ways, 3.0/3.5 seems like a unification, clarification, and refinement of a mess of sub-systems already in the game. It's sometimes referred to as if it was a big break with AD&D, but it seems like AD&D was were it began in the first place.
(I skipped 2e in here, as I've barely done more than crack the covers of the 2e books. I stopped playing AD&D right when 2e was starting to get rolling, and didn't look at D&D again until I co-authored a dual GURPS/D&D 3.0 statted article with Bob "Coyote6" Huss for Pyramid magazine).