I don't even know how to argue this. Who would you consider a great Olympian? Who would you consider the greatest and why? Phelps has shown consistently in the last 3 Olympics that he stands out among the other Olympic athletes (of all sports) by demonstrating absolute dominance in his sport. Can you name another 3 athletes that are similar? How about just one? Outside of the Olympics, he's also dominating the entire sport of swimming rather than just one or two events. What he's done at the Olympics is mindboggling. He's not out-touching his opponents by fingertips. He's destroying them by full body lengths or more. This would be like an Olympic boxer coming out and knocking out all of his opponents with one punch.
As for swimmers swimming multiple events in one meet...yeah, they do that and it's absolutely brutal (try sprinting a 200m butterfly...) On top of that, regular swimmers also don't face fresh world class specialists in each event. Some of those specialists show up and only swim one event (i.e. Ian Crocker) before hanging it up for the rest of the meet.
Fair? Equating swimming to shotput or f*ucking rifling is unfair. If you're basing the media hype about him being the greatest Olympian solely off of his medal count, then I'd say that the media's focus on the number of gold medals he has is doing him injustice. Medals aside, his dominating performance alone would net him the title of best Olympian. A shot putter would have to throw his shot out of the stadium in multiple Olympics to impress the way Phelps is impressing.
Do I sound like some fanboy? Hopefully not...but as a swimmer, I'm flabbergasted at what he's doing. Everyone in the sport is. I know records will get broken over time, but I also figured they'd fall by hundredths of a second at a time...not 2 second smashes.
On another note, I can't believe 10m air pistol is an Olympic sport while softball is being eliminated.