Do you know how much rock music has declined in popularity? As far as I can tell, there's been ZERO truly mainstream bands to break out in over a decade. When I saw truly mainstream, I don't mean you have to be a juggernaut like Coldplay. Bands like 3 Doors Down, Good Charlotte, Jimmy Eat World, Evanescence, Puddle of Mudd, Sum 41, etc. were "mainstream popular". We know what they look like, they have some radio staples. This is something you can't say about recent bands. We just don't get new bands who even just drop 3 top 50 hits and make some memorable music videos and then fade out.

So when was the last time we had one of those? Imagine Dragons is a big mainstream band no matter what you say about them, however their first album was in 2012. Mumford, Florence, Vampire Weekend date back to 2000s. Bands like the Lumineers and the 1975 that would be borderline for mainstream relevance anyway are still 2012/2013.

The normie explanation for this is that well, over time people's taste change. Just like how the popular movie genres 20-30 years ago were different like R rated comedies and adult thrillers and stuff. But, I think this is weirder. Because rock music should be protected by variability in genre. Motley Crue, Nirvana, Matchbox 20 have nothing in common with each other music wise, hence logically, this should've protected it. Hard rock goes out of style, well girls still like the band with handsome guy singing radio friendly pop ballad. Which is exactly what happened most of history. But somehow, none of them are popular anymore. There's no bands at all really even if you stretch rock definition, no new Maroon 5 (they've been around as long as Avril Lavigne and still seem chart relevant). There is not too many rap groups, but I think that happened by 2000s.

Therefore, my theory is the explanation must go beyond generational taste change, it's about change in views towards white guy-isms, masculinity, lesser socialization, etc. Yes in another decade perhaps Lewis Capaldi would've released Someone You Loved as a Good Goo Dolls type of band, but in this era it made more sense to be a solo artist, although it's not like there's been tons of hits like that which you could envision released as a band, no individual version of rock stars. Maybe people who are really collectivist about society and into "The big group" see less meaning in "the small group" of 4-5 bandmates if that makes sense. Hence why for example internet sites with millions of users like reddit and twitter are popular and little enclaves on the internet like personalized forums are less popular.