well it is not quite like this.
Sata can be installed without any floppy if it is set to function in basic mode (as in standard ide ). If it is set to raid mode or ahci xp instalation needs to know the controller drive provided by floppy

Seting sata drive to native (basic) or ahci or raid is a matter of bios options which are not allways included on the motherboard
Even if old regular p-ata (ide) hdds are set in raid mode the xp install needs to have provided the controllers drive