interesting but i don't think that will do our hobby much good if we all left the fry in the tank as the numbers available will be significantly less. in the wild the fish have plenty of space, not 200L to share with all inhabitants so the mortality rate could be higher.
If i use my trophs as an example, there is a group within the group that does the breeding. Keeping trophs, you generally need large numbers to spread the aggression so the runts that may not be very good for breeding later are excellent for keeping the numbers up in the group. horses for courses i guess, they all have their place in the small societies we keep them in.