This is just because you are used to windows and it’s issues. I’ve been using Linux for 15 years now and I think this about Windows. It works great, in particular for some specific applications, but it is a pain to use. It is slow, lacks customisation and you always have to install drivers for any device you want to use. Plus those updates are really annoying when you don’t boot Windows for a long time. You can’t use your computer while they are installed and of you have a lot of them it can take a really long time. I’ll never switch to Windows!

If you run immich with docker, you can choose any drive/folder for your photos by mounting it at the right location inside the docker container.

However, I would strongly suggest that you also use some other kind of backup beside rest. I personally like restic combined with Backblaze B2, but there are many other good solutions for this.