That’s only because you change the questions you are willing to answer as soon as we find a flaw in your arguments.
Before the great PR gurus came up with the moniker “mirrorless”, all cameras that were not DSLR were labelled either “compact” or, sometimes, “mirrorless” and you were forced to use the rear screen. But then marketing gurus invented the term “hybrid” to describe any camera that used an EVF rather than having to use the rear screen.
Ergo, according to those definitions, the D780 is not a hybrid because it doesn’t use an EVF. Using the rear screen makes it into what is essentially a compact camera and using the OVF makes it a DSLR.
Canon makes it clear when they say…
In use, the difference between Mirrorless and DSLR cameras, stems mainly from how you frame your subject.
For example, an EOS DSLR will always have an optical viewfinder, as well as an LCD screen. Canon Mirrorless cameras will always have an LCD screen, but not necessarily a viewfinder. If there is a viewfinder it will be an electronic viewfinder.
So, Canon state that, on a truly mirrorless camera, If there is a viewfinder it will be an electronic viewfinder
And this definition is not unique to Canon. Here’s Nikon’s headline blurb on the D780…
Let nothing stand between you and your vision. The D780 gives you everything you’d expect from a pro-calibre DSLR, and then some. A clear view. A long battery life. A tough build. Plus two fast, reliable AF systems, phenomenal tracking, wide ISO range, and more. Freeform or staged. Stills or movies.
From their technical specifications page…
Type - Single-lens reflex digital camera.
The most accurate way of describing it is that it is the same as any other preceding Nikon DSLR cameras except, in LiveView, it offers the same on-sensor auto-focus and auto-exposure mechanism found in their Z6II mirrorless camera.
Based on your hype-biased opinion, my D100, D200, D810 and D850 are all “mirrorless” because, when I choose LiveView mode, they don’t use the mirror. The difference with the D780 is that it uses the same on-sensor auto-focus and auto-exposure technology. But that doesn’t make it any more a mirrorless camera, even in LiveView, than any preceding Nikon DSLR that has LiveView capabilities.
And, if you read further in many writings on the D780, you start to see that the “mirrorless” technologies in LiveView seem far more connected to video shooting where fast response and focus tracking are far more important.
Now to a practical consideration of using LiveView.
Before going to all the trouble of setting up all your LiveView settings, did you think of seeing what happens when you press the shutter in LiveView? Did you notice that the rear screen goes black for a second before the shutter actually fires? Do you understand that this “blackout” is because the sensor has to be “discharged” from its “viewing” state back to zero before the shutter can be opened in the “taking” state? Have you thought about how that delay might affect the ability to regain focus when shooting in burst mode? How do you track the subject on the rear screen when you can’t see anything?
This is common to the majority of “mirrorless” cameras, not just the D780.