I mean, I feel I can learn to play fast riffs without the need for a metronome. Creativity stiffler! lol. What if every drummer played and learned all his fills to a metronome? He'd play as if he had a stick up his rear. Same on guitar in my opinion. Timing will ensue accuracy.
I think I've got the stregth and accuracy to play a riff to speed but have to play is slow to get it right. And then slower STILL to get it perfect. Monotonous, stupid guitar.