Ducttape,

It is about having alternatives. What kind of equipment gives
you the most good alternatives?

During an emergency situation, you may have to leave your car.
(If you did not leave your car, you would not need pack at all;
a bag, or bags, carried in the hands, and stored in the car,
would be fine.)

At that point of leaving your car, you want the alternative of
carrying more than a small day pack will hold. If you have a
4000 cubic inch internal frame pack, you have an alternative:
load it heavy or light. The pack itself does not weigh much,
but you could have a day pack, in your car, as an alternative, also.
I would take the 4k ci pack even if it was half empty; I might
need the capacity later. You might choose differently, Ok.

"Travel light" and "move fast" sounds like an adventure;
and indeed you see it a lot in fiction books and movies.
If the protagonist had proper gear, there would be no story,
i.e. no adventure.

"Travel light" can actually create the adventure; if you do
not believe me, go into the woods with what is in your pockets,
and stay 5 days. You will have an adventure.

Go into the woods for 5 days with an equipped backpack,
and you will probably just have a good time. If you do have
an adventure, it will not be for lack of gear and supplies.