I disagree with your blanket statement. The vast majority of (commercial) PC games were never that small, even in the 3.5" heydays. Most games required 2-10 disks.
PC? what pc?
Every single NES game or CGB game would fit on a floppy. More or less all GBC and SNES games could compress down to a floppy
When PC really took off as gamming platform against Amiga and Atari ST, shipping games in CD-ROM was already a thing.
Amiga had plenty of single disk games.