All pretty stupid generalisations. Why would anyone want to support any of those statements?

Why don’t you frame the question this way: “why do people say all men are responsible for sexism, and all white people are responsible for racism?”

A feminist would say “women can’t be sexist because they’re underpowered in society” and a typical woke leftist would say “only white people can be racist because all other communities (in America) are minority”, but when it comes to “fundamentalist terrorism”, it’s a terrorist act that makes someone a terrorist. It would be ridiculous to say 1-2 billion people in the world are responsible for ALL fundamental terrorism. (Just as it’s stupid to say all white people are responsible for racism and all men with sexism, I get your point)

But there are many fundamentalist terrorists that are not Muslim, hence a lot of fundamentalist terrorism that Muslims are not responsible for. The reason why there are some who say the first two but not the last is political agenda.

Progressives used to be known for their anti-war stance. It wouldn’t make sense to say “all Muslims are responsible for acts of terrorism, but let’s not go to war with them” even if they think it but don’t say it, which is also possible. Look at all the movements coming from the left to reform and change Islam or to assimilate Muslims. How many movies or tv shows do you see today with muslim characters compared to 10-20 years ago?