Intel 8080 was launched in April 1974 and the development system for it, "Intellec 8 Mod 80", was available soon after that.
CP/M could be developed only after the launch of the 8080 and the delivery of the development system.
In UNIX, the environment variables were added in the Seventh Edition (1979-01), together with the Bourne shell.
I do not remember whether any other command interpreters used something equivalent with environment variables before the UNIX shell (excluding the interpreters for general-purpose programming languages, like LISP and APL, where you can run a function in REPL and that function can access global variables).
Therefore the quoted year may be a typo for 1979, when environment variables appeared in the UNIX shell, but were not available in the CP/M Console Command Processor (CCP, the predecessor of COMMAND.COM).
CP/M 1.0 was demoed to Intel in 1974, but they didn't buy it.
iCOM FDOS was the first operating system that was available to people, and it sure didn't have environment variables.
Anyway, these operating systems didn't have multiple directories. But you could use CP/M 2.x's ASSIGN command to bind a logical name to a physical name. Minicomputer operating systems had this, also IBM mainframe had JCL DD commands.
CP/M could be developed only after the launch of the 8080 and the delivery of the development system.
In UNIX, the environment variables were added in the Seventh Edition (1979-01), together with the Bourne shell.
I do not remember whether any other command interpreters used something equivalent with environment variables before the UNIX shell (excluding the interpreters for general-purpose programming languages, like LISP and APL, where you can run a function in REPL and that function can access global variables).
Therefore the quoted year may be a typo for 1979, when environment variables appeared in the UNIX shell, but were not available in the CP/M Console Command Processor (CCP, the predecessor of COMMAND.COM).