It's funny you mention this as I had a very similar thought the other night when clean-installing an old gaming PC to try some VR stuff on.
I'm used to using a Mac, and the update notifications can definitely be annoying, but Windows' default update behaviour is another level of excruciatingly bad UX. I assume — perhaps wrongly — that you can stop windows from installing updates on shutdown/restart. However, the other night (on Windows), forcing an update on shutdown was the only obvious option available to me. I can't fathom what the rationale is to force this kind of experience on users.
When I want to shut my computer down, it's because I want it to turn off, not start a new (oftentimes looping) operation to install software that I won't immediately see (or need to see) the benefit of.