Why are fighters able to fight after they have failed drug tests for PEDs? Anderson Silva for example, is about to fight as if nothing ever happened and people will be cheering for him like any other fight.
His career means nothing at this point, he's a cheater and should never be allowed to fight again.
Because MMA fans recognise that if they were to suddenly stop supporting fighters who took PED's that would pretty much involve no longer supporting every hero they had grown up following.
If you are going to hold a grudge against fighters who took PED's you pretty much have to remove the entire history of MMA from your mind.
However, there is a cutting off point, a point a which people think its no longer ok to take PEd's.
Different fans will have different ideas of where that cut off point is, some may have it a couple of years ago and therefore why they dont like Silva being active, some may have the cutoff point at last July, or last October, or January 1st this year, some may apply the cutoff just to active fighters and give everyone from the past who has retired a pass, some have no cutoff point.
My own personal cutoff point is to an extent active fighters. If you get caught now then sorry, your legacy is gone, you dont have me as a fan. But, people do make mistakes a lot also depends on how they conduct themselves in regards a positive test, to they hold their hands up, say i cheated , I made a mistake or do they drag the case out for six months and put up a ridiculous defence.
Personally, I assume that anyone from the early days of the UFC (100 and prior), Pride etc was on steroids. I dont hold it that much against them, there were no tests and if you gonna put temptation in peoples way they gonna take it.