> Why haven't local-first apps become popular?

The Immich "Quick Start" step 1 is mkdir and wget commands. Step 2 is "Populate the .env file with custom values"

I get it, when the prerequisites are 1) run a server and 2) have Docker installed, but this isn't inspiring confidence that local-first apps will become popular.

Self-hosted services and local-first apps are distinct topics. Local-first is about keeping data on clients- orchestrated via a centralized or distributed system. Usually it means installing an app that works offline, and might sync to desktop. Self-hosting is about running servers in owned or rented infrastructure, and that is never a turnkey proposition.