I'd agree that most baseball fans don't really understand roster rules such as waivers and the 40-man roster and the Rule 5 draft. For the average baseball fan, those things don't really matter all that much. But if you're playing a baseball management simulation, those sorts of things become much more important.
A few comments about the Rule 5 draft. It has been held, in one form or another, since 1903. The idea behind the draft is the same now as it was then: teams should not be allowed to "hide" players in the minor leagues and impede their progress toward the major leagues. Right now, the rule states that a player who:
- is not on his team's 40-man roster; and
- has been in the minors/majors for at least four years if he was signed after his 19th birthday; or
- has been in the minors/majors for at least five years if he was signed before his 19th birthday
is eligible for the Rule 5 draft, which is held during the MLB winter meetings in December. A player taken in the Rule 5 draft must remain on the drafting team's 25-man active roster (not just the 40-man roster) for the next season. If the team wants to demote him, it must first offer him back to the team from which he was drafted.
Now, you can say "that was very enlightened of the owners to care about struggling minor leaguers who couldn't break into the big leagues because the teams that held their contracts wouldn't make room for them." Maybe. But, at least in the beginning, the owners wanted a chance to sign players whose contracts were held by
minor-league clubs. In effect, it was an organized form of player poaching as the MLB clubs snatched players while paying only a fraction of their value to their minor-league clubs. Later, when major-league clubs started owning farm clubs, the Rule 5 draft became a way redistribute talent from teams with deep farm systems (like the Cardinals) to teams without (like the Browns). In short, there may have been some concern for the players when the owners instituted the Rule 5 draft, but the owners were mostly looking out for the best interests of the owners.