Is completing onboarding a fake metric for user activation?

Noticed a weird pattern recently.

A lot of users finish every onboarding step look around for two minutes and then never log in again.

Meanwhile some people just click skip on everything find one useful feature right away and become daily users.

Tracked completion rates for months thinking it meant success but it doesn't seem linked to actual retention at all.

Are you guys trcking onboarding steps or actual value moments to measure activation?