A random thought that popped into my head while watching a Metallica concert clip this morning

It has been over 40 years since Metallica debuted.
If we take the period around the 90s, when Metallica was at their peak, as an example: people like Elvis, Chuck Berry, or Little Richard, who were active about 40 years prior to the 90s, were treated as being from a completely different era, regardless of their musical achievements.
But looking at it from our current perspective, would Metallica—who enjoyed their prime 40 years ago—be treated as that outdated? Not really.
Just looking at their concerts, young fans are still flowing in, and their music still feels youthful.
I suddenly found myself wondering: is this because of the metal genre, because of YouTube, or is it simply because it's Metallica?