FreeDOS is used by PC OEMs for tech support, e.g. https://support.hp.com/us-en/document/ish_9586495-9586656-16
You can create a DOS-bootable USB flash drive by downloading and saving a FreeDOS operating system image. The bootable USB flash drive can then be used for testing and troubleshooting any component on your PC.
FreeDOS helps sell PC hardware without the expense of a Windows license, for customers who would like to install Linux, OpenBSD, or separately licensed Windows, e.g. http://h10032.www1.hp.com/ctg/Manual/c02628224.pdf