I think the problem has always existed, but to a much lesser extent than it has in the last 3-4 years. Vintage has always had the bulk of deck's value in Power 9 and lands, and the only recent changes there have been things like Mystic Sanctuary ($1 card), Cavern of Souls ($10 when it came out in 2012, now $50), Urza's Saga ($40), etc. Legacy & Modern also rely on an expensive but versatile land base, but in terms of staples they've both been hit hard by stuff like Modern Horizons 2 where stuff like Ragavan, Urza's Saga, and the elementals (Fury, Endurance, Subtlety, etc) are so pushed that they warp the metagame drastically. I can't think of a time when that was case in a way which impacted so many different decks. Some cards were problematic (Oko!) and made specific decks that included it much better for a time, but I've never seen a single set impact modern in such a big way.