I was unaware that it was a part of D&D as i never seen it in any of the games that i played- and i played a lot, albeit it seems to be limited to sorcery?
Yeah, Pathfinder grew out of 3/3.5, in which metamagic were all independent feats that you could take on any caster that met the requirements. They were stackable, and brutally strong, and the increased spell level limitation wasn't enough of a rein on them - even quicken, which had, I think, a 3 level increase spell modifier, was still quite broken even with that adjustment (spells scaled with your caster level, so using haste and quicken let you cast 4 large 3rd or 4th level AoEs in a turn, but they all scaled up much stronger than their base level innately, once you were casting them as a high level character - it was obscene).
By 5e, more restrictions were put in place to limit that massive burn potential, but they were over-zealous with some of the rules, applying them universally, when it was only specifically the quicken metamagic that needed the consideration, once haste was adjusted as well.
I'd like it if the metamagic feat was repeatable - so that a wizard who wanted to gain all of the metamagic options they liked could spend feat value to get them.
