PCA factor $\frac{1}{n-1}$

Question

I've seen multiple PCA derivations where the $\frac{1}{n}$ (for variance) or $\frac{1}{n-1}$ (for sample variance) is just omitted, e.g. here. I see that they are proportional to each other but is this just something they did to make the derivation easier or is the scaling factor not necessary in practice?