There are always alternate participants brought along in case of illness or injury to the main players.
As it is, one of those gymnasts (Susini Lee) won a gold medal in the exercise where she replaced Biles.
Biles is not the whole of the team. She is not the only gold-medal gymnast on the team. The amount of scorn heaped on this young woman for making the responsible choice is despicable.
Yeah, but you know how it is - every armchair quarterback sitting at home knows better than every world-class gymnast anywhere and any time. 
Yes, yes she did. She stepped down to avoid 1) injuring herself, which would have had a terrible effect on morale and 2) to let someone else (like Sumisi Lee) have a chance at a high score/medal that would help the team.
If someone on a team can’t perform for any reason the responsible thing is to not perform, especially if there is someone who can take their spot and do better than they could on a particular day.
Yeah, she should have taken that course on precognition so she would have known last month (or whenever) that in the future she would have a problem. Geez, guy, it’s not enough for you that she’s among the greatest gymnasts every, you now want her to be psychic, too.
Who is praising her “like she won gold”? All I’m hearing is “good for her for taking care of her mental health and not risking an injury.” Og forbid we acknowledge she did the right thing, is that what you’re saying?
No, it’s a mental health issue that became apparent while she was competing during a vault where she did a 1.5 twist instead of 2.5 twist because she lost her orientation in the air. A flub that mere mortals such as ourselves might not notice but was noticed by her team mates, her coaches, and the judges. She initially tried to power through it but couldn’t. So she did the responsible thing and withdrew before she hurt herself, got crappy scores for the team, and so on. While there could not be a complete replacement for her a couple other girls did get the opportunity to do more than they originally thought they would at these Games. I’m OK with all that, why aren’t you?
You are wrong. “Shell shock” can come on suddenly.
Are you unaware that Biles - along with a LOT of other young women - was sexually molested by the team doctor, Larry Nassar? Are you unaware that through this very year USA Gymnastics was insisting that the Olympic team continue to train at the very place where much of this abuse took place? Do you think that maybe, just maybe, some of this is past trauma catching up with her?
At this point I’m not really speaking to him, I’m speaking to others who might be reading this thread.
Someone with as many medals and wins in her past as Ms. Biles is in no way a failure no matter how much you want to portray her as such.
Her team doesn’t seem to have a problem with her decision, why do you?
As for her country… given the high percentage of mouth-breathers and idiots why should any one care what the armchair quarterbacks think?
I can’t either but here’s an example of what can happen to a gymnast on a bad day.
Given how Ms. Biles honestly has been received I very much doubt prior withdrawals due to twisties were ever publicly called that in the media before. But I would not be at all surprised if other competitors had stepped down - or been withdrawn by their coaches - for that reason.