I think that the internet has allowed for an increased globalization and saturation of music that is going to make it much harder to achieve that kind of lasting power. All of the various technological advances we have now mean that anyone can make music.

Additionally, most of the artists that get named as idolized from 50+ years ago tend to be American or British (at least in Western society). With our increased globalization, k-pop bands can now be the new Beatles for Western society (in terms of fan phenomena) in a way that they couldn't 50+ years ago. When you add in the fact that what was able to become mainstream 50+ years ago was much more limited for a whole host of reasons (access, sexism, racism, etc.), it was definitely easier to become Elvis Presley than it is to become [insert artist name here] today.

I also think that the increased number of genres now means people's taste in music is much more individualized. There wasn't "math rock" or "dream pop" or any of the other niche genres in the same way. I see a lot of people mentioning King Gizzard in the comments and while I think they're a talented band, I think they're too niche to the point where a lot of people haven't heard of them so they likely won't achieve that mainstream lasting power.

None of this is to say that there aren't artists right now making awesome music--it's that there are so many amazing artists making music now that you can't have a few standouts like you used to.