Most people DO use one, though, because that's how you access the iCloud services that underpin the Apple ecosystem. But it's not MANDATORY.
My understanding is that you cannot even log into a Windows machine without an MSFT account. That's a big difference.
An Apple account together with an iPhone and MacBook let’s you share clipboard, passwords, notes etc., a no brainer.
Windows laptop and iPhone? I guess an Apple account still is more useful here too, actually. So the average user does not really need an MS account, hence the annoyance.
You can also still log in with a completely local account as well. It takes a few extra minutes to set up but once configured it works fine.
The system is full of dark patterns and roadblocks that steer users towards an MS account, but you don't have to use one.