There’re a few reasons to use the Mac Base System:

It can help to recover or restore your macOS. Yet if your Mac is continually crashing, stalling, or popping up with error messages, then you might need to use the base Mac system. System failure is never what Mac users hope to encounter. Sounds intriguing, right? But how do you know when you need to use the base system? Keep reading. If you’re having ongoing issues with your MacBook, it can help repair or erase your hard drive, install a new version of OS X, and restore the device from a Time Machine backup. It's basically a recovery partition that contains a minimal structure or slimmed-down version of a Mac Operating System with the essential components only needed to run and restore macOS (including System Preferences, Dock and Finder). If you've booted up in Recovery Mode and accessed Disk Utility, you might have come across the mysterious OS X Base System volume. I've put together this no-brainer guide that explains what it is as well as when and how to use it. If you have many unanswered questions even after googling what macOS Base System is, you’ve come to the right place.

Can reset macbook pro os x base system