Old systems only ran one program at a time (basically). So boot floppy for OS into RAM, then load program floppy(s). Do the thing, save work to yet another floppy. Close program, maybe have to re-insert an OS floppy (ala MS-DOS). Then new floppy for next program. Only a king a 20MB RLL drive.

That's right I owned an Atari STFM with 4MB of RAM.

As another example You could easily make RAM disks via a desktop menu, to facilitate the common setup of a single built in floppy drive. So you could copy files off into RAM via the GEM desktop GUI (literally drag and drop) and then put another disk in etc.

Random aside: I accidentally found that this machine would transmit audio over FM radio for a short but very useful range automatically.. blew my mind as a kid. I could never find anything official about this online later so not sure if it was an intentional design, poor EM design of the audio chip, or a hack of my particular 2nd hand franken-tari - either way it was super useful to have wireless audio in the 90s.

One disk, sure. 30? Well, the parent made a very biased interpretation of history, depending on what one means by "old". I remember running Linux on a 4 MB RAM computer, and how good upgrading to 8 MB felt.