The best argument I have come across for the fairly widespread existence of Islamophobia is this. Americans simply refuse to care that China is mistreating and brainwashing its Uighur Muslim minority.
Lots of supposed 'opinion leaders' have argued that Americans should care, the response ... cue the crickets. I speculate many view this as one disliked population abusing another disliked population, 9/11 made an impression.
It's an example of "Why don't you and him fight? I'll hold your coat." One of those situations where people wish both sides could lose.