That's .. pretty much how the home computers of the era worked? BASIC in ROM doubled as the shell on many (most?) systems. It's also how the file manager in the article works.

You only use line numbers in BASIC when typing in complete programs. If you type in commands interactively, the are without line numbers and executed immediately. How would you otherwise use commands like LIST to list the current program? BASIC only had one active program at a time.

So on BASIC machines with file systems you could list, load and store programs this way. Of course file systems only made sense once you had random access storage. Floppy disks were a lurury item in this space for a long time, and on tape you would manually position the tape before reading and writing. Most home computers at the time also didn't have the concept of folders, because storage was so small anyway, so file access wasn't that complicated.