Age of clutch is irrelevant.

If the clutch is not releasing properly, it will be hard on synchros.

If the driver isn't using the clutch properly, or trying to ram gears too fast...it will be hard on the synchros.

Basically anything that is keeping the input shaft spinning when the clutch should be disengaged..will cause it to be hard on synchros.

Of course the other possibility is totally wrong oil.