I don't like electronics at all.However,it's an interesting question.For OR operation standard circuit,there are two diodes which are forward biased in 1-1 state.I cannot draw the circuit here;but anyone familiar to the circuit undearstands that even if the two diodes were not there, the OR operation could be performed.Then what is the function of those diodes?
In which case ask somebody familar with the circuit; "even if the two diodes were not there" makes no sense otherwise. It is possible to connect the collectors of two transistors to a common load but you can't usually feed two amp ouputs into an input because the outputs then feed into each other and burn out.
Is this the circuit you mean? (positive logic) Please Register or Log in to view the hidden image! (from HyperPhysics) If the diodes weren't there, then the two inputs and the output would all be tied to the same voltage. If you tried to set A high and kept B tied to ground, then you'd have a short circuit to ground and A would stay low.