Yes its especially true for non-white backgrounds. It all has to do with contrast. With black on white we have 100% contrast, if we use dark gray on light gray the contrast becomes say 70%. The lighter the contrast the easier it is on the eyes. Here's a quick example of what it looks like.
Interesting link, but you're missing the point. The website even misses on their points. Most of the bad examples fit under an acceptable contrast ratio, by the standards given in their research, and even their good examples are not pure #000 or #fff. The w3c states that a minimum level of 3:1 works for people with 20/20 vision and 7:1 achieves the Triple-A standard. To show you what it looks like.
You're describing someone who's lazy, not a 21 year old. The point is to give that person more time to do whatever they want. If you hire the right people they wouldn't be the type that play video games and drink all day.
Hold on, who are you to judge people on that? If someone wants to drink and play video games all day on their fifth day, then good for them! If they are producing quality work, then what does it matter? There is this obsession with productivity in the US and the startup community in general that I find incredibly distasteful. People are already risking their financial lives for startup businesses and you're going to come on here saying that's not good enough. That's typical Silicon Valley hivethink.
Maybe you need to get out of the office more, bud.
Remember he was targeting 21 year olds. As a 21 year old I can confirm that not all of us just drink and play video games. As I said "The point is to give people time to do whatever they want." I don't care what you do or how old you are, I'm just not going to be sitting on my ass all day when I could be doing something productive or be "out of the office."