I could be totally off-base here, but it seems to me the two games are like peaches and nectarines, similar in a lot of ways, but still very different.
SOM is terrific for "baseball nerds" who want to re-create past seasons and match up one roster against another to see what would happen if they played each other in real life, either head-to-head or by yourself. Realism is very important.
SOM online on the other hand, is a resource allocation puzzle, where we try to maximize runs scored vs. runs allowed differential by picking players based on value relative to their performance potential in their home park and divisional opponents. A person can only have a passing interest in baseball realism, but love playing the online game because they enjoy analyzing statistical probabilities and it appeals to a competitive nature to build a better team than the other guys.
I think it's possible many of the people that absolutely love the board game hate the online version, and vice-versa.