A custom engine in place of an unsupported page builder
The old site ran WordPress on a page builder that had lost support, on an install old enough that every fix worked around a dependency with nobody upstream. We proposed replacing the platform with our own engine, and the client approved it. The argument we made was that a purpose-built engine gives this business what a general-purpose CMS or an off‑the-shelf builder cannot hold for it here: a modern, fast site with no plugin stack to keep compatible and no theme update that can break a layout.