You rely on Netflix in HD, you have no PC to fix boot loops, or your model is a carrier-locked variant.

The ASUS Zenfone 9 is a unicorn in the modern smartphone era. In a world of phablets and glass sandwiches, it offers a compact 5.9-inch screen, a headphone jack, a side-mounted fingerprint scanner that doubles as a smart key, and near-stock Android software. For the average user, it’s a perfect daily driver. For the enthusiast, however, the real magic lies behind a locked door: the bootloader.

You are a tinkerer, you want to run your phone for 4+ years, or you need root for automation (Tasker, Macrodroid).