SPORTSMANSHIP NO COOL ANYMORE?

Regarding the team sports: what is the psychology behind never helping your opponent say, get up when they're knocked down? This is not a 'back in the old days rant;' it has appeared increasingly to me that it is a mandate for players to never, ever help up or give a hand or affirmative gesture in any way to an opponent during a game. I know the easy answer about toughness, posturing, 'psyching out,' et cetera, and I know that's all been around for ages, but it also SEEMS to me that it is a universal expectation that you never give an inch of support, affirmation, compliment, or a literal helping hand up to your opponent to an increasing degree. Am I wrong?

I'm not asking if it's a new thing, but if it has a) increased over the years and b) if it's an implicit or inferred idea, or one that stated clearly as an expectation.

Also, is it too late to fill out a bracket?