You're not wrong, just misinformed, as virtually no one adhered to the more-recent OS change when the dealers moved up the BA date to 1984 (Secret Wars??? ), wanting to turn "worthless early-Copper" into "valuable high-grade late-Bronze" - that was *before* Copper took off and I bet they regret that stupidity now.
I would estimate the majority of informed, longtime collectors would select 1979-81 as the End of the Bronze Age and 1981-82 as the Start of the Copper Age.
There are just too many seminal books (Warrior Magazine, Love & Rockets, Marvel Graphic Novels, Pacific, etc.), events (New EiCs at Marvel/DC, creator royalties/ownership), changes (no more cartoon books, horror comics/reprint titles all cancelled, Warren/Spire/Harvey shuts down, Contest of Champions starts mini-series wave), etc. for Bronze to go too far out of 1981.