I agree with you on copyrights in general, but I'm not sure that's the issue here.
1. Movies and their sequels/prequels: If anything, copyright should make it easier to make NEW stuff. But while there's lots of interesting movies being made (check Youtube and tiktok and vimeo etc, and even the mainstream streaming services which have tremendous long tail of weird content!), as far as cinemas specifically go - that's less and less where we watch our video entertainment, attention span is lower and lower, and people are choosing safe choices with their limited money and time, so cinema-oriented companies are making tremendously expensive visually impressive safe content. I can watch experimental interesting stuff at home. I go to cinema at cinema prices for a safe movie that has astonishing special effects that I cannot feasibly watch at home. It's an outdated medium, but that doesn't mean art itself is dead - it just moved to new forms.
2. Music may well be a discoverability problem. There's a RIDICULOUS amount of new stuff being made. Experimental and traditional, interesting and boring, in all shapes and formats and kinds. Go to reddit and see the amount of cool stuff people make at home. But it's also positively overwhelming... whereas I know I like Sultans of Swing and will always like Sultans of Swing :). And we have to consider who is the paying audience and how they pay - is the cool stuff teenagers and youngsters watch and listen to captured through traditional channels? Cool new stuff has always been shared and bootlegged.
So I think cool innovative art is being made all the time, more than ever in fact; but not necessarily much or all of it is being consumed and importantly tracked at mainstream level. And that may be OK and normal. The article is looking at outdated art format/consumption, and noting that they are showing outdated content. It may be more tautologically true than an enlightening/warning sign.