Yes, but then again, how many people actually compete for the decathlon? I think sports with very few competitors—skeet, badminton, etc.—are eliminated just on that score.
If we’re talking about best athletes, it may well be that LeBron James is the best all-around athlete in the Olympics (but I wouldn’t credit him with being a best Olympian).
I think you might want to look for a combination of strength/speed/skill, with lots of competitors, that wins his/her competition running away, if you will.
Not to mention, most decathletes are "jacks of all trades, masters of none." They do a bunch of skills well, but in most of their individual events, other people excel far better.