Yeah, it’s definitely not the most precise thing. It’s good to around ±1mm. I tried to measure 1.75mm filament with it, and it just reads 1, not even between 1 and 2, so for critical measurements the physical matches are definitely better.

And yeah, here the vernier effect is not giving very high precision; it’s just giving a way to space the marks out enough to be printable, but indicate movements that are as small as a printed line.