I do take issue with the prevailing modern mindset that these things are commonplace, however. Replies like "well duh, you just use the table in Dragon #28" is all too common a statement around the sphere, conveniently ignoring the idea that it's fucking bonkers to just assume someone has an easy-referable copy of Dragon #28, as if we're all sitting on some archival library of early works. Or worse - the assumption that we all memorize every single piece of D&D ephemera from eons past, somehow.
You are not wrong. Older D&D material was scattered and hazard (Dragon mag, etc.), but that's because it was growing organically in real-time. No one had even the remotest template (talking 0e/1e days) for what was gold and what was fool's gold. That's why it was such a vibrant time. I've made the analogy before with regards to open-source software in the early aughts (e.g. Raymond's
The Cathedral and Baazar). The OSR was a renaissance (rebirth) too (around the same time, both facilitated by the new distribution mechanism of the early internet) and grown in "bazaar" mode. We are now deep into "cathedral" design-mode, orchestrated by WotC and in typical fashion, it's slow, heavy-handed, and---to be honest---uninspiring.
Circling back to your point: yeah it's a mess, and no one can really expect you to know all the arcana---but rather than a condemnation, I look at it as part of the fun of the (original) hobby.
Primarily, I like digging for knowledge (I'm a reserach engineer) because it's so rewarding when you add another uncovered relic to your collected database. This is, after all, a
hobby. Hobbies are not things served up for effortless consumption (i.e. consumer products, movies, etc.), but something your fiddle with out of sheer joy and interest. Hobbies are suppose to take time and effort, although I can see where rule-hunting might not be everyone's favorite aspect. Incidentally, this may be why rule-light versions of the game probably don't hold one's attention for quite as long, whereas something like AD&D campaigns go on for years and years.
Secondly, there's a social aspect of having to sift for info. We are all here to support each other's searching through the rubble of the ages to find those obscure elements we need for our next play-session. It's why we're on this forum, satiating that basic desire to trade tips at Byrce's generous marketsquare.