Few of them have access to run code on real hardware, so they will often develop their software using emulators.
The reasoning behind using emulation instead of real hardware was cost and demand.
This is a necessary part of the development process, since absent this ability they would have no way to test their software on real hardware.
They also work at a low-level, using timing information about the real hardware that the task will execute on, with all its specific features.
This option allows the operating system to be booted on real hardware.
This is never a problem for a commercially developed game: upon required testing on real hardware, the bug would quickly be discovered and fixed.
Using real hardware early in the design flow.
May be used of real hardware or software to imply that it isn't worth using.
Current use includes virtual machines which have no direct correspondence to any real hardware.
It doesn't seem like it's on a trajectory to ever be shipped on real hardware.