Why does last-click refuse to die?

Why does last-click refuse to die?

It has been declared obsolete for fifteen years and still anchors most reporting. That persistence deserves an honest analysis rather than another dismissal.

The case against it

Last-click — assigning 100% of credit to the final touch before conversion — systematically over-rewards harvesting channels (branded search, retargeting, coupon sites) and starves demand-generation. It is, structurally, a bias toward whatever sits closest to the wallet.

Why it survives anyway

— It is deterministic and auditable. Every stakeholder can trace exactly why a conversion was credited. Multi-touch models, by contrast, are often black boxes that finance teams won't sign off on.
— It is stable. Probabilistic models reshuffle credit as their training data shifts, which makes period-over-period comparison maddening.
— It is consistent across the industry, so benchmarking against competitors and affiliate payouts stays comparable.

The nuance

Last-click is a bad attribution model but a defensible accounting convention. Affiliate payouts, for instance, need a deterministic rule everyone agrees on in advance — fairness and disputability matter more than causal accuracy there.

What to actually do

— Keep last-click for settlement and payout where determinism is the requirement.
— Add a parallel data-driven or incrementality-calibrated view for budget decisions, and never let the two reporting layers fight.

Bottom line for practitioners: don't kill last-click, demote it. Use it where auditability is the job, and use causal methods where allocation is the job.