The shower at home is not meant here, of course. To shower in the nude is a challenge for some people, if it does not take place at home.
Before you enter the pool, you have to shower. Naturally nude, because otherwise a body cleansing in the anal area, where a lot of bacteria are present, is not possible at all. If you have a look, how many bathers actually shower without their bathing suit upfront, you will usually get a figure at 1 % or below. The remaining 99 % spread their bacteria in the water – ruthlessly and with impunity! Therefore, so much chlorination is reuired.
What is the reason? Convenience may be a reason: once you have forced yourself into the bathing clothes in the changing cubicle, you do not want to put them off again for the shower and put them on again afterwards. Almost nobody gets to the question: "Why ever put on bathing clothes – you could simply bathe naturally without bathing clothes!".
Our acquired shame as to the body is the main reason. Also in the shower, the shame as to the body has influence: you do not show the sex and excretory organs to others, even if the situation in the shower is taken as a self-evident exception. However, many people do not manage to do the self-evident.