Ask HN: Is above the fold enough (UX)?

[downplay]

When Ubuntu (the Linux/Gnu desktop/OS) moved the window buttons over to the left hand side it was frowned upon by the community. Top left placement is supposedly better from a usability perspective: buttons say in the top left, have more predictable placement and are easier to reach with a pointer (if you just throw the pointer to the top left), having buttons in the top left is good for cascaded windows etc.

I've noticed an annoying trend with popular websites. They place things like Sign in and Sign Out in the top right corner. And even with my modest laptop screen size, I sometimes struggle to find them - as they are found slightly off-screen. In part I think this is deliberate.

Yahoo mail has even followed suit. Stackoverflow has a rather irritating search box placement of top right. When I'm slightly zoomed in on that site, I have to scroll to the right to use it.

So I ask: is this a bad usability trend? Can we push essential controls back to the top left for crucial functionality, for us left to righters, top to bottomers?