What do you think the reactions of a group of students who take Maths, Chemistry, Biology, and Physics would be if a guy walked up to them and said 'Hey, I'm STEM too, I do Electronics, Computer Science, Geology, and Statistics!'?
Yeah, they technically count as STEM, but they're not real STEM. They're not what people typically associate with STEM. It's like saying humans are animals. Yeah, they technically are... But they're different.