Your suggested alternative of moving all photos to a laptop doesn't work for the people who prefer having all their photos accessible from their smartphone. That's the usable UI that the constant sync to cloud services gives them. The tradeoff is the cloud storage subsciption costs.

Also, transferring all photos to a laptop creates a single-point-of-failure if the laptop dies. Recovering photos becomes even more complicated when the internal SSD is encrypted with macOS File Vault or Windows BitLocker. Yes, photos in cloud storage isn't really a "true backup" in the 3-2-1 best practices sense but it's still more durable against catastrophic data loss than a single laptop.

The self-hosted Immich photo server is just one way to enable smartphone access to all photos and avoid paying for cloud storage. That's the reward for the "overkill" setup.