As far as I know, this isn't as bad as everyone tends to think. I kind of accept it along with the engineering culture- I prefer to be responsible for my projects rather than wait til 9am to put out fires. But I may be biased as a young, single, and so very poor student considering working for Amazon. If anyone has a better idea of the work/life balance at Amazon, I'd be grateful to hear more.
aaronbrethorst hit the nail on the head- there is a definite benefit to starting at a large software company. For me and my friends whom are looking for our first FTE positions, startups are daunting due to impostor syndrome. In my case, I don't know if I am skilled enough to jump right into a niche startup and be relied upon so heavily to ship. Amazon, Microsoft, etc provide a great place to learn from very intelligent people in the industry.
I think as my specific social circle is reaching the twilight of our 20s, those environments are less and less appealing for a lot of us but a few wouldn't trade it for the world.
My Microsoft friends are A LOT happier -- they have a much more balanced schedule, are not expected to be available on a moments notice and feel much more relaxed at their job. The friends I know at Amazon are very rarely off at a normal time, have a lot more pressure from the higher ups and have to regularly take high quantities of "on call" work.