In short, it is not simply that unique 4-card caps did not exist, but if they had existed at the time Limited Edition was released, they would have rendered large swaths of the set unplayable in 1993
Suddenly, each 1/1 deathtouch for 1 mana becomes a threat, effectively having toxic 2, so to speak
Deathtouch creatures make every combat step a dangerous proposition, while your removal keep opponents on the defensive
Rootha, Mastering the Moment Rootha, Mastering the Moment is an easy one to get behind because hasty evasive tokens can be a win condition on their own
Ajani, Outland Chaperone does less buffing, but generates lots of little creatures and has some of white's conditional removal
Cheat out Items at a cheaper cost through Belle, Inventive Engineer