@Animesh you can always use http://lab.arc90.com/experiments/readability/ or similar if you are upset that an individual blogger may use an alternate font. I see no reason for content authors to become sheeple and cookie cutter. A tool like that will help provide the no frills or suprises dry impersonal experience if you wish to have it.
Personally, I respect their font preference, after all, they are providing knowlege their free to us. If I blogged, I'd use my fav font too, I dont care what font an author chooses to present their nuggets. I'm just grateful they are willing to share. But hey, by no means am I trying to speak for everyone or change anyone but I've never had a problem with it.
Peace yo.