First, as people have noted, if one man can win 19 gold medals, the events are way too similar in their physiological demands. There's no way around this.
But it's the ridiculously small talent pool that irritates me. Only a very small segment of the world's population ever has the opportunity / wherewithall / desire to compete in swimming. Swimming is just not part of most humans' cultural world in the way that running is.
Imagine if, because of economic and cultural factors, track and field had next to zero participation from Africans and people of African descent. Nobody from an Arab culture. Very few South Americans. If the participating population were reduced like this in track, the 5000m performance list for 2016 would be:
13:11.8 Illias FIFA
13:12.7 Ben TRUE
13:12.7 Antonio ABADÃA
13:13.3 Andrew BUTCHART
13:15.6 Ryan HILL
13:19.3 Brett ROBINSON
13:19.4 David TORRENCE
13:20.7 Galen RUPP
13:20.7 Sam MCENTEE
13:20.9 Patrick TIERNAN
13:23.1 Garrett HEATH
13:23.7 Florian ORTH
13:23.9 David MCNEILL
13:23.9 Jonathan DAVIES
13:24.1 Lucas BRUCHET
13:24.3 Sean MCGORTY
13:24.3 Eric JENKINS
13:26.2 Andrew VERNON
13:26.8 Cameron LEVINS
13:27.3 William KINCAID
13:27.6 Thomas CURTIN
13:27.8 Tom FARRELL
13:28.9 Takanori ICHIKAWA
13:29.1 Brian SHRADER
Now imagine that this subset of the world population was reduced further to ONLY those individuals who had access to a pool and money for instruction prior to age 10. Maybe 80-90% of the above list goes away. 13:25 may make you a medal contender.