A short ingredient list is genuinely useful. If your skin reacts to things, a serum with almost nothing in it is easier to troubleshoot — there are fewer suspects.
Niacinamide has real, specific evidence: it strengthens the skin barrier, reduces sebum, and fades hyperpigmentation by blocking pigment transfer into skin cells. That is not marketing — it is some of the better-supported cosmetic ingredient science there is.
$6. For an ingredient this well-evidenced, that is remarkable.