A rematch clause is essentially an insurance policy. You don't take out insurance expecting the worst to happen, you take it in case that thing happens. For example, what if Terrance Crawford gets disqualified? Horn is not obliged to fight him again. What if Crawford gets stopped due to a cut or suffers a freak injury in the ring (see Haye v Bellew for a recent example of this happening) Horn could just say "I won, you lost" and refuse to fight again. It could take years for Crawford to get another shot.
Further to this, a rematch clause does not apply unless it is activated. It gives a fighter a RIGHT to a rematch, not an obligation. So all in all, there's no reason why a fighter or their advisers would prefer NOT to have a rematch clause; if they didn't want to fight again they wouldn't have to, but they would have the option to if it was desired. The only reason you would not include a rematch clause is where the bargaining strength of the parties is roughly equivalent or where a rematch clause would stop a fight from being made.
Further to this, a rematch clause does not apply unless it is activated. It gives a fighter a RIGHT to a rematch, not an obligation. So all in all, there's no reason why a fighter or their advisers would prefer NOT to have a rematch clause; if they didn't want to fight again they wouldn't have to, but they would have the option to if it was desired. The only reason you would not include a rematch clause is where the bargaining strength of the parties is roughly equivalent or where a rematch clause would stop a fight from being made.
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