I read the parent as saying that the course covered these at all, not as complaining that nothing else was presented.

But continuing on that train, what would you want from mentioning alternatives to a theoretical framework? A framework is just a different way to look at the world that you can discard if it's not useful.

To give a programming analogy, if a course does a module on JavaScript exclusively with react, they're not teaching that vue, angular, or svelte don't exist and you should only use react. It's much more likely a statement that react is common and useful for people to be familiar with when they go into the outside world. Covering the long list of alternate frameworks, many of which the teacher will have never actually used in a serious way, is both difficult to do in a useful manner and takes away from the limited time available to cover what they can with sufficient depth.