Dont know what your point is.
It all boils down to rev matching and the force behind the gears.
If the revs are matched exactly then the method really doesn't matter. But, if the revs are off, then it does. With the clutch disengaged then one side has little force behind it and the dogs can engage without much problem. Like putting on the rear wheel and matching the splines.
With the clutch engaged both sides have a great deal of force behind them. If revs not matched then the dogs will "grind" at each other until they are matched.
The dogs are a wear item and are intended to be replaced when the transmission is rebuilt. Length between rebuilds depends on how much they have been abused.