Perhaps, but that doesn't mean you can't drop down the experience earned per hit by a level-dependent fixed percent in Combat and Training Rooms. Basically you would earn more fighting a Horner Reaper in combat pit than say, a dwarf, but it is still quite a bit less than actual combat experience gain.
Training Room:
Level 1-2: 15% Less than Combat
Level 2-3: 20% Less than Combat
Level 3-4: 25% Less than Combat
Level 4-5: 30% Less than Combat
Level 5-6: 35% Less than Combat
Level 6-7: 45% Less than Combat
Level 7-8: 70% Less than Combat
Combat Pit:
Level 1-2: 5% Less than Combat
Level 2-3: 5% Less than Combat
Level 3-4: 10% Less than Combat
Level 4-5: 10% Less than Combat
Level 5-6: 15% Less than Combat
Level 6-7: 15% Less than Combat
Level 7-8: 30% Less than Combat