As much as it's about winning the medals, this is about setting personal and world records, too.

Regardless, they have to make do with what they have. Nobody is moaning that the weather affects triathlon timings.

If the organizers controlled the weather and made it rain, people would absolutely be complaining.

People are complaining that the local g varies, though. https://www.xkcd.com/852/

Right, if you are swimming in multiple events then it doesn't necessarily make sense to swim as hard as you can in the early events if that is going to tire you out for the latter events.