Its only the team that didn't take the ball into contact who would want to do this. The team that took it in will be trying to create a ruck to generate an offside line to keep the opposition back.
The only way I can see this working is for the tackler to "roll away and stay away", and/or to not get to his feet in the tackle area (ping) and/or for there to be no tackle assist, and therefore no-one for a team-mate of the tackled player to come into contact with while on his feet. This is not going to happen very often.
I agree the ball carrying team want to create the ruck. It is to their advantage.
Easy to create - tackler just needs to release and not prevent the ball being played (not material affect on play - so play on). Or roll away out of the way (such that when they get to feet they cannot be "bound in").
The risk is the Referee decides (incorrectly) it is a ruck, when it is not. Also risk is the ball is so quick, your defence isn't properly aligned. Plus risk the front of the tackle is not properly defended - leaving a pick and go option risk. But if done properly - the ability to shut the attack down quickly, and behind the gain line is huge.
The team that I saw do it, had a clear call for it, and were very effective at cutting out the #9 to #10 channel, preventing quick wide ball, so allowing the defence to concentrate on the close attack, giving more time for the wide defence to get in place.