I have been using Magisk since almost 12 years now when I first started rooting and unlocking my bootloaders and using/creating my custom ROMs. Magisk allowed for managing root access to applications, install modules that allowed for functionality that is not available otherwise, access the android application’s process space using Zygisk, lsposed and associated modules, etc. Without Magisk, if one had unlocked bootloader and rooted his/her device, it would be a nightmare to manage root access and host load of applications will start failing because of the “compromised security”.