The point is that everyone thinks (even internal people) that this is an extra step. I was talking to a very senior person about a failed installation after talking to two others. I’ll bet it’s even jnternal urban legend.
Next time I talk to someone that isn’t reading a script and knows internals, I’ll ask again.
It may have started as an easy way to get users to reboot again (a second time) and turned into being ‘different’ when it isn’t. I’ve been asked to reboot again many times and I don’t object. Some people (not saying you) might say ‘why’ and having this ‘deeper’ reboot would make it easy to save time in the usual tech support conversations.
I’ve done tech support for decades and anything that prevents balky clients is a help. (There used to be an ‘unplug the cable and blow the dust off of the connector’ line. This was to be sure you actually did pull power.
My tech quite readily said there was no difference and all it did was (of course) make sure the car wasn’t in motion. Since you can reboot while driving, that’s irrelevant anyway.