We have had Rapid Fire, the channeled Focus builder, since BfA.
We have had Trueshot, which used to be called Rapid Fire, since Vanilla.
They are not remotely the same ability.
Rapid Fire, the channeled Focus builder, feels out of place in the rotation. If I wanted to spend 15-25% of my combat time channeling, I’d play a Shadowpriest.
Give me instants and hardcasts. Burst damage. Individual large hits.
THAT is what MM has been about since the beginning.