Is it? Don't like to play devil's advocate but I'm pretty sure my Instagram is pretty much alive and my BeReal feed is an at all all-time high, with several new joins lately too.
I agree that it's much worse, that on anything that isn't BeReal it's harder to find your friends posts, that the ads got way too many - but at least here people are absolutely not stopping to create content for them.
if you red even the first sentences, you will see that the author doesn't claim that there are NO posts. they say that most of the posts are not social media anymore but corporate designs