Whenever I see this topic come up I have to shake my head and think, "here's someone else trying to justify keeping more fish than the tank can safely hold." The issue shouldn't be can they survive together, but will they thrive together. An excessive amount of juvenile fish in a smaller living environment is, in some ways a natural occurrence (kinda) since juvenile fish do stick together for a period of time when in the wild. The difference is water quality and the impact on their development. Large fish (CA/SA cichlids) do not with the exception being breeding.
Water purity aside, fish packed tight in a tank will show slower growth and in some cases more susceptible to disease. As an example I have four P. Fredrichsthali in a 100 gallon tank and two in a 300 gallon tank with four Blue Labridens. All of the fish were in a separate 300 grow out for the first part of their life growing out together...and the same size. The fish that were "crowded" into the 100 gallon tank are now smaller by almost an inch than the fish in the larger tank. I wouldn't consider the 100 small for four fish...but the point made is that a smaller container will yield smaller fish.
Fish release phermones in the water that lets all of the fish in the tank know how many are in the body of water. This might explain a lack of aggression in an "overcrowded" tank...like fist fighting in a broom closet. The second thing to consider is that in a smaller tank territories become blurred...putting the kabosh on natural cichlid behavior. Not to mention that you always have that chance that one of the fish could snap and do damage to the other fish in the tank. They may not be aggressive all of the time, but it only takes once to create a disaster. I can only speak for myself...but if I put some time into raising fish properly I don't want to roll the dice and hope their eternal piece...between my CICHLIDS. LOL
So...my two cents...it's not a matter of could it, but SHOULD it. 65% may have agreed, but I don't see that many folks posting results. It's just a poll. Fish can't respond to a poll. Practice responsible fishkeeping. If you have more fish, get more tanks.