ad_hoc
(she/her)
Works to a point; the fighter needs to be able to hold the monster in place. 5e doesn't do this well.
You need a very careful balance - the effect need to be big enough to care but not so big it can't be powered through, except that it also needs to be hard to power through, but not too hard...
Basically, people need to be constantly arguing whether it matters. That's when you've hit the sweet spot.
Not only does grapple reduce a creature's movement speed to 0 but the grappler can then move that creature around.