I am just about to set up my new Linux machine, which will be used to convert analog video and audio to digital video and audio. Is there any reason why I shouldn’t run the system off of a live USB stick (say, a good quality one from Sandisk), that is, without installing Linux on the hard drive and not setting up a boot partition, a system partition, and all that?
That’s a totally valid use case, I have done it in the past and there are Linux distributions that are made to be used this way. Those distributions usually work by loading the whole system into ram which avoid multiples writes to the USB stick. They also usually offer some persistence mechanism so that data can be added on the USB stick.
Examples of distribution meant to be used this way: MX Linux, Puppy Linux