Tina,
  Thanks for the thoughts.

I would say that I agree with this post ... to a point.  But that's only because the poster points out the variety of ways different writers handle the issue. The 'argument' if you will, is with his or her last paragraph here and the assumption that  "...most stories today are written in scenes portrayed through the eyes of a single viewpoint character, whether first person (I) or third person (he/she). In such cases there is no need for any extra punctuation to signify a character's thoughts. The whole scene is, in effect, the thoughts and perceptions of the 'viewpoint' character. The example below - written in a third-person limited viewpoint - may illustrate why extra punctuation for thoughts is usually unnecessary."

This one statement neatly cubbholes all (or almost all) fiction writers into one mold - the one where the stories are written in "scenes portrayed through the eyes of a single ... character...' along with the subseqent argument that this single viewpoint perspective makes punctuation superfluous.

If, in fact, the story is written in first person then, yeah, you're likely to require no punctuation to set off  the character's thoughts because, as the writer pointed out, all of the narration is the charater's thoughts.

In the case of third person, however; virtually everything is outside the omniscient or limited omniscient POVof the 'narrator' and so virtually everything would need to be set off in some way to delineate a character's thoughts. In most cases, particularly in third person, this can be easily handled, most of the time, with "he thought".  But if you are dealing with a limited omniscient POV, then you will likely need to find other ways of presenting a character's thoughts and motivations.  Most of the time, particularly if you are dealing with several sentences or a short paragraph, using italics works best. If it is just a few words, or one sentence, using the attribution method (he thought/she thought) would probably be the best method.

And, sometimes, the reader likes to feel 'special' and get inside the head of a character. Giving his/her thoughts, clearly exhibiting that it is this character's thoughts, adds to the sense of 'getting inside the head'.