Serdar Somuncus jokes are actually really clever compared to meme-culture "Hitler did nothing wrong".
PDP didn't make a "Hitler did nothing wrong" joke however. He made a shitty joke referencing another person that is a actual known anti-semite. A bad joke that was terribly handled, but still.
But that's the whole issue.
A WWE wrestler can be a total heel in the ring, but a nice guy when not doing their show. Similarly, a comedian usually gets the benefit of the doubt for the jokes they crack on stage, yet what they say while not doing a routine can be held against them.
Again, Youtubers evoke the appearance of being a regular person who just shares / plays games in front of the camera. They interact with their audience, there is no kind of unspoken understanding that everything they say and do is part of a routine.
They vlog, they do draw-my-life stuff, they talk about current events. Clearly the idea is to evoke the impression "this is me, i am a geniune person", which has a big appeal to the young audience. The target is always to have the audience think you're their 'friend'. (or in this case, "bro"). They look up to them. "Regular guy, just like me, makes big bucks by playing video games." - did you miss the defense force for the guy who LITERALLY ADVERTISED HIS OWN CSGO CASINO TO MINORS.
In that setting, i simply don't feel it's appropriate to lightheartedly use these kinds of phrases and jokes.
haven't followed MacFarlane or any accusations about him so i can't comment on that. But yes, if Peter Griffin says "i need a jew" because he has money problems it's obvious satire because he's portrayed as an obvious asshole, dumbass.
When MacFarlane says "Whoa, where did all my money go, i better fetch me a jew", he deserves to be scrutinized.
I feel the 'contract' (of what constitutes satire, what's a joke) between the viewer and the joke-maker is much more clear in a show about fictional characters
The vast majority of his non-gaming content is comedic in nature, with him constantly doing different persons and different voices when he wants to make a joke where he isn't acting like himself. It's not like he all of the sudden started doing comedic bits.