This seems to overlook the more obvious reason he is absent from that narrative: he was never all that popular. His only top 100 hit, for "Hallelujah", came in 2016, after his death.[0]
Yep, the album Various Positions on which Hallelujah appeared was not even released in the US by Columbia, they released it in Europe instead.
I think it was only after Bob Dylan covered Hallelujah ~1988 at one of his live concerts, he was the first to cover it (John Cale did it in 1991), that the song and the album exploded in popularity.
it's safe to say he was always a cult favorite at least since the mid-90s when I first heard of him. Mainstream writers of all sorts (music press among others) have certainly been writing about him for as long, for the same set of reasons he's being written about here
[0]: https://www.billboard.com/artist/leonard-cohen/; compare to Elvis https://www.billboard.com/artist/elvis-presley/, Beatles https://www.billboard.com/artist/the-beatles/