Out of curiosity, what is stopping these platforms from being able to learn from users? For example, when I say something to Siri / Alexa / Home that they canno

Out of curiosity, what is stopping these platforms from being able to learn from users? For example, when I say something to Siri / Alexa / Home that they cannot process, I would love to be able to manually train them to perform an action and have them "learn" this new feature. (Something along the lines of, "ok Siri, whenever I say 'blah blah blah', open this app, go to this page, hit this button, tell me the content in this box") Obviously this is not an easy task, and maybe it is being worked on already. Thoughts?