Yes that is true, but if there is any risk for a stressed animal getting another infection the use of it as a prophylactic is warranted. An ill stressed animal will not fight any infection very well or at all and any help is better than no help.No no!
Antibiotics as prophylactic are not a good idea.
That encourages resistance so when they are sick the antibiotics will not work as well (or at all).
Also, it doesn’t work. Giving antibiotics kills bacteria. They kill the good ones and the bad ones (which is why they often cause tummy upsets). But they don’t hang around waiting to kill a bad one should it show up at a later date.
Seriously, not a good idea!
It’s the same debate for using an antipyretic on a fever, there is the train of thought that the fever is there to kill off the infection, and the other that states reducing stress from pain and fever will help to encourage the body to heal faster.