Actually grub 0.x series had much more useful rescue shell tab completion than the latest release. You could easily list all boot devices, partitions, and even filesystems and their contents. All from the rescue shell. Consequently, you could boot into Linux and reinstall grub in the MBR to fix it. All that without using a boot CD/USB! Good luck doing that with the latest version of grub and UEFI.
Also getting into the BIOS on legacy firmware was also very simple. On most machines it’s the three finger salute followed by either F1, Delete or rarely F11 or F12.
The boot process was simple, and the BIOS had just one simple task: load and execute the first 512 bytes of the disk that was designated as the boot device. That’s it.