Booing happens everywhere. A lot of the people complaining on reddit are Americans, and American sports are quite partisan. Elite athletes competing for silver at the Olympics should be able to handle booing.
Maybe, they should be able to handle some booing. Doesn't make it appropriate behaviour to force them to go through it, as hosts. It's an event whose entire premise is to rise above partisanship in the name of sportsmanship, we can expect a little more sportsmanship from the crowds too.
Nobody is forcing anyone to go through it (except North Korea maybe?). If an athlete cannot handle the booing, he is welcome to skip the Olympics. I agree that the whole thing would be so much better if the crowds were nice, but it is what it is.
I didn't mean parent countries were forcing their athletes, I meant Brazil, as the host, are not living up to reasonable expectations on hosts of an international sporting event. You say it as if all athletes were given due notice, and agreed that they would take racist, partisan abuse. The crowds are uniquely, surprisingly bad. The answer to this isn't "you're welcome to leave", that does not deflect blame from the way Brazilians have been behaving. And just saying "it is what it is" downplays just how far below basic standards of decency such booing is.