I'm quite sure the earliest examples of damage caps go back far further to the old random events. The perfect example is the Strange Plant, which had a damage cap of 3. However, if attacked with full guthans it was possible to heal 25+ even if only 3 was hit. Further, the healing and the damage seems unrelated (it was possible to heal 25+ on a hit of 1 also).
The old randoms also had exp modifiers that caused you to get only 10% of the regular exp you would normally receive.
The 6000 damage cap stated is not up to date. I regularly hit over 6000, and occasionally over 7000 with Meteor Strike while Berserk is active. I started soloing the corp only around 6 weeks ago and have never seen hits capped at 6000. Maybe there is still a cap though I use every benefit I can to max damage other than wearing torva since superior tetsu and seasinger hood is worth using more than a little extra damage (overloads, turmoil, dual drygores).