What are FRC's in Guilty Gear for gameplay wise?

I’ve been reading about Guilty Gear since I’m trying to learn about fighting games I haven’t played. So when I came across FRC’s over at dustloop I failed to understand what exactly it is and why it’s in the game.

All I understand is they cost less meter and can only be done at certain times with certain moves. But what I don’t understand is why this is a gameplay feature. What is it adding that normal RC’s don’t?

fighting games nowadays have huge emphasis on efficiency of meter usage. some characters like slayer in ac can almost kill someone with a proper frc combo. halving the amount of meter required is nothing to ignore. sounds basic but it makes a big difference. also it’s been a while since i played gg but iirc you can also frc whiffs while regular rcs don’t allow that. the flipside is that frcs have a notoriously short input window.

it’s kinda like a reward for learning your character better, you don’t have to be sitting on as much meter to open up lots of possibilities. plus they’re not exactly easy to do. missing your FRC drops your combo, wrecks your meter or leaves you open, so you’re making a pretty big bet on your timing when you do them.

you can cancel whiffs and projectiles, too, which is pretty ballin’. you can do a bunch of crazy pressure and mixup stuff with ky if you FRC the big fireball.

There are also some FRCs that can be used on whiff, in situations that you can’t RC.

Examples are Ky’s 236x, Ghost Zappa’s 236x, unsummon Zappa 6HS, Slayer 214P/K, Johnny mist teleports, etc.