But at the same time Scheme is limited to academia and has near zero practitioners outside academia. So the Scheme ecosystem is tiny compared to Python or Java.
Yes, you could argue, that "Computer Science" is not mere "Software Development" and academia shouldn't bow down to industry and shouldn't be a tool to provide "programmers". But again it's also important for motivation to apply the language, algorithms and concepts in other fields. Learning also has to do a lot with motivation and experimentation.
And this is a "hot take", but I always had the feeling back then, that courses are often bound to the professors curriculum and sometimes their books, so I am not surprised about resistance to changing the language.
That said, I was glad, when the Scheme lectures were over. Now I am a Software developer for more than a decade and have to admit, that learning Scheme didn't make me a better programmer at all. If I'd stayed in academia I might have a different opinion.