How could you make fusion monsters with no generic materials work in even past versions of the meta without cheating them out? The probability of getting everything necessary is extremely unlikely and would and has been phased out in favor of easier strategies with better payoff.
I mean they were always sort of a novelty or part of a gimmick prior to like the ARC-V era being much more generous with materials, yes, of what I recall.
Before ARC-V, you were basically running HERO Fusion Box thanks to the manga, or Cyber Dragon relying on a slowly growing number of same names.
Otherwise, Decks just happened to have some a Fusion Boss or two, you'd happen to have Poly and if you managed to draw/have all the parts, well there you go, Bob's Your Uncle.
It started off as a cute bells-and-whistles gimmick, that you could maybe do, and eventually became more central for Decks to be able to as time went on.
Design and power creep.
They weren't meta, they were just part of the game's flavor.
