Irrelevant. The truth is, both OSs are designed to give you a basically usable, interactive system before all startup tasks are finished. There's no reason not to this since it doesn't matter if you get a shell prompt before e.g. sendmail is started - even if you manage to write an email in the interim period, it will simply be queued until sendmail is started. But it's not a "deception" when Windows does it; everyone does it.

Imagine a car that didn't let you drive until the aircon had reached the desired temperature...