Has anyone tried a legal challenge to the word "buy"? It seems like a straightforward case of misrepresentation.
That won't fix the core problem though - the platforms will just use another word for it and you still won't be able to take your content with you on a vacation or give it to your friends and family. It's a massive degradation of consumer rights you had guaranteed with physical media.
While streaming media has some notable conveniences in certain cases, the downsides to the consumer seem to outweigh those benefits. It's as if there is a coordinated assault on ownership rights across many industries which is being led by the ubiquity of actually-broadband internet connectivity, the streaming technology that exists across many industries (gaming, movies, music and even general software) paired with corporation's insatiable desire for growth at all legal (even some not) costs. Because they now can, they will.
As one who prefers freedom of use to maximum convenience I think it wise to purchase physical media when possible and back it up in a manner which is suitable to your long-term accessibility needs. Maybe I'm just a crabby old guy...