Why? Because unlike Xiaomi, OnePlus, or even Samsung’s Exynos variants, vivo actively engineers its bootloaders to be hostile to third-party development. This article is not a simple "how-to." It is a deep dive into the architecture, the locked bootloader problem, the MTK advantage, and the fragile state of custom ROM work for this device.
If you are looking to "work" on your phone to fix a bootloop, remove bloatware, or change the Android version, the most reliable path is flashing a Stock ROM (Official Firmware) using the SP Flash Tool.
If you want deeper access without replacing the whole operating system, you can choose to root the stock system using Magisk or SuperSU patches. This setup gives you access to custom kernels, battery saving profiles, and system-level audio mods while keeping the base system stable. How to Restore Official Stock Firmware