And when was that or are you going to play semantics where you shift the definition of modern laptop to meaning a "modern laptop made by Apple"
The silly picture from DED shows the Air and Pro. At the time of release the Air was neither thinner or lighter than other laptops that preceded it. Thinkpads predated the ibook by 7 years, Sony's X505 from 2004 is lighter than Apple's (2008+) Air and only slightly thicker. Both devices look like a laptop to me.
And, from memory, Apple had to withdraw the claim that the Air was the thinnest laptop ever after someone noticed that a Toshiba laptop which had been released years earlier held the crown.
So what's the "modern laptop" era?
I think you misremembered the "thinnest" claim. Sure a discontinued Sharp was thinner but the MBA was thinner at its thickest point compared to this. Fact is the MBA ushered in the ultra book computers.