An N95 respirator is rated to block at least 95% of 0.3 μm particles. It’ll do waaay better than 95% at blocking droplets! They’re much larger.
(though N99 and N100 respirators do exist)
But remember that a respirator blocks 0% of particles getting in your eyes.
I believe face masks are only 95% effective at best and that's only with a proper N95 which a lot of medical staff appear not to be able to get hold of. Hence they're wearing things like Buffs or cycling masks to make do. In that situation, having another layer that can stop droplets etc. from reaching the mask in the first place makes sense to me.
Plus it stops a whole lot of messy body fluids from reaching the mask and goggles which cuts out a swap/clean cycle (again, difficult if there's no spares!)
[Edit to correct 'googles' to 'goggles', FFHS]