How do you fix a high sign-up rate with low feature activation?

In our early stages, we celebrated every spike in sign-ups, assuming sign-up growth equaled product adoption.

A few months later, we noticed a frustrating gap: users were creating accounts, exploring for two minutes, and leaving without reaching their aha moment. Our onboarding flow was trying to explain everything at once instead of guiding them to the single core action that delivers value.

How do you simplify your onboarding flow to boost early activation without hiding the deeper functionality power users need?