> Why make them bold?

It's an Indian thing. And I can say it cos I am also Indian (American), so don't cry "racist".

I worked with quite a few off-shore devs during my internship at Goldman and I noticed this in a lot of blogs and GH Project README.md / Landing pages of my off-shore Indian peers. I even asked a couple of them and they said "SEO!". But I've read on mattcutts.com and other SEO blogs that bold-ing / making keywords strong is no longer a factor in determining SEO Rank, atleast with google.