A ban on lifting tackles is not only hard to enforce, but also may have unintended side effects.
The reason gang tackles are so frequent is that there are no rewards for an old fashioned legs tackle but also because modern players are bigger, stronger and more skilled, so a lot more goes into stopping them. Tackle low and every player can offload nowdays, go high and they usually keep the legs pumping. It's a team effort to tackle powerful runners. Then there is the all important slowing the ruck. That's why gang tackles are the norm. Almost all tackles require some lifting. A lifting ban is hard to enforce, refs have enough on their plate without having to judge whether someone should be sin binned for a dangerous lifting tackle. Thats why a penalty is sufficient, and the judiciary can work out who's at fault and what punishment is required. To do that on the run will cause huge problems in our game. Thousands of lifting tackles happen every year, injuries are relatively rare and major tragedies like this are once a generation thing.
Sometimes rules designed to do one thing have unintended consequences. No punching has led to more grubby play, speeding up the ruck rules has made it actually more slow and messy. A blanket 3 match ban on any shoulder charge was a disaster of a rule. A rule that has been forgetting is the rule introduced in the early rounds of 2014, the wrapping legs in a gang tackle. In recent years cannonball tackles had become a problem and were rightfully outlawed. But then the nrl went 1 step to far. They banned any player coming in amd wrapping the legs of a player when there was already other defenders in the tackle. This rule was championed by Wayne Bennett mainly because Alex McKinnon had suffered an ankle injury in one of these tackles. What would happen is that 2 blokes would tackle high, but a powerful runner would keep pumping his legs and making metres, so a 3rd man would come in, wrap the legs, get him to ground. This was bizarrely outlawed early in 2014. So what we had was a situation that if 2 bloke had tackled a man high, and he was still pumping his legs a third player couldn't wrap his legs, so his only option was to grab the bloke by the hips/thighs and lift him to stop momentum and get him to ground. Because of a stupid rule brought in to supposedly stop injuries, we saw a rise in lifting gang tackles with tragic results. Not long after the McKinnon accident the wrapping legs penalty has been completely ignored.
The whole thing is a freak accident. 3 players in a lifting tackle, not helped by the rules of the time, and a guy still fighting in the tackle ( i hate the whole he ducked his head trying to get a penalty, i think it was more reflex to avoid face planting).
I think that if we start tampering to much with the lifting rules, it would lead to an increase of wrestling tactics and may make tackles even more dangerous