I just watched the clip.
Here's the thing. Other than a couple one-off appearances, Led Zeppelin hasn't existed in 43 years. The guy on the far right looked like he's in his 40s, but the other two appeared much younger. If you're a classic rock fan, then it's a big duh, but if you were born in the late '80s and raised in the '90s and '00s on, e.g., hip-hop or country music, why would you have any familiarity with LZ album names or know what they looked like nearly half a century earlier? There are an awful lot of artists who existed only before I was born that I wouldn't have recognized when I was 40. Hell...you could probably come up with a Garth Brooks album and show me a picture and I'd just sit there blinking my eyes, and he was HUGE during my lifetime.
The social media comments about "societal failure" and what-not are predictably stupid.
Also, I'd say Plant is the most recognizable of the four in the picture they showed, but he obviously looks nothing like that now.