Did you see the US medal list ? More than 80% come from swimming.
There are way, way too many swimming events at the Olympics. If you're capable of swimming a decent 100 and 200m freestyle, you can compete in 5 events (2 single and 3 medleys) and that's just wrong.
Birgit Fischer needed to compete in 6 Olympics to be able to even compete (let alone medal) in 12 events.