The fascinating thing there is how Wizards "tricked itself" by misreading how certain cards form gamebreaker combos. So then they embarked on an elaborate "currency value adjustment" program, aka Type 2. (With all the spinoffs etc. In my areas "1.5" and "Legacy" and so on were never very popular.)
By being relegated to "Type 1" All those power cards were effectively cordoned off into a backwater, and lost most of their effective value. Then as the years rolled on, once cards left Type 2, they also dropped in value like a stone.
Well, except that this didn't happen. Yes, a number of cards definitely lost value once they fell out of Type 2 - but the price of the core type-1 power cards has never actually gone down, and in fact Legacy has meant that a number of secondary cards from that era have now skyrocketed. A white-border Black Lotus will set you back more than a thousand dollars; a black-border one you'd be lucky to find under two thousand. All the dual lands are north of $50 in white-border now and more than $200 in black border; half-blue duals are at least $5-600 each in black border. Some of the cards from the earlier sets (esp. Arabian Nights) have seen corrections, but that's more a matter of the market realigning itself around playability rather than just rarity - old out-of-print cards that see any tournament play at all (or even saw tournament play at one point) have skyrocketed (Karakas at $50-60, Sylvan Library at $25, etc.)