2024 Player's Handbook Fireside Chat

[Eldariel]

Alot of things in 5e existed in prior editions but got shoehorned into a particular class.
Metamagic is probably the one that most annoys me, but there are others scattered through the game, for better and for worse.

Battlerager I don't specificly remember but in 3.5 spiked guantlets and armor just existed without needing to be a class feature, and some of this existed as worldbuilding background prior to that.
As I recall bladesinger was contextually a fighter/mage multiclass back in AD&D but my memory is foggy.

So Battlerager was a Prestige Class in 3e Races of Faerûn and a Warrior kit in AD&D Complete Book of the Dwarves. Bladesinger was also a Prestige Class in Races of Faerûn but also Tome and Blood and Complete Warrior in 3.5. In AD&D 2e I recall it's in the Elf book though even 1e Elf-class is pretty much just Bladesinger.

Battlerager even featured in some of those Drizzt-books; that Thibbledorf Pwent or whatever.