We tried to solve the open-source revenue equation. We failed

Not so much "failed", but "discovered SaaS revenue is harder than consulting", which, to be honest, every software entrepreneur knows.

It's always far easier to sell your hours than to sell a product. Hours are more flexible, don't have the "round peg, elliptical hole" problem that many products do, and give the customer more control (and thus are an easier sell). Of course, as the author details, selling hours doesn't scale.