Why do people get offended at the idea of putting blame on an entire group for one bigot?

[Anonymous]

for example when hillary called trump supporters a basket of deplorables, everyone including white liberals got offended but trump supporters go on a racist rant after trump says something racist and stupid and the same people who defended trump supporters absolutely said nothing even though they attacked hillary for calling trump supporters for who they really are. Another example of this is when a white person who is white and a racist, why do people always have to say "not all white people are racist" or if a christian is a homophobe why is there always one evangelical that gets mad at being called a homophobe for that one individual who misbehaved and is paying the consequences of their actions at being a homophobe. Why should we not hold an entire group responsible for the actions of one individual bigot?

[MadKez]

It's emotions playing