But shouldn't come usability before design?
The progress bar within does work, because the user enters the address right there and at the moment where he presses enter, his eyes are still in this area, so he recognizes the progress bar immediately. A unmissable loading bar would solve the problem, as long as it is unmissable (from my point of view).
Yes. If I saw data showing that 20% of youtube users didn't see the red bar, for example, I would agree with your point. But I have 1) my own experience showing otherwise (not worth that much) and 2) the logical argument that youtube probably did some usability tests with good results before releasing this. These 2 points are not a definitive argument, but they're enough for me to be skeptical of your critique.
> The progress bar within does work, because the user enters the address right there and at the moment where he presses enter,
But this is not the case when a user clicks a link at the bottom of the page, and a new page starts loading.
Agree on that one.