It's less about how it's harder to wrestle 'new' sounds out of a guitar then the fact that the tools to make electronic music are flat out easier*. It's not as if lots of EDM/Hip-Hop/Pop are using drastically different drum sounds or synths...but EVERYONE has those tools (laptop, shit even a tablet/phone) as opposed to getting a traditional instrument and gear which can get pretty expensive quick.

There's also the issue that mainstream rock bands made themselves uncool going into this century; rock radio was on mediocre bands like Creed/Nickleback. Heavy metal, the supposed bastion of guitar based rock music, was full of 3rd tier Korn and Limp Bizkit biteoffs. The emo/pop punk revival in the mainstream helped a bit but those bands were so steeped in pop songwriting that it definitely didn’t feel like rock music. Really the only big hard hitting rock band in the classic sense of the word that seemed to gain stature and prestige during the 00’s was the White Stripes and they were half novelty**

That said, you can argue rock music exists and is arguably thriving; just not in the form we think of. There is a precursor to this. Years ago Bob Dylan going from acoustic to electric guitar signified the change of guard from folk music into rock music.

https://en.wikipedia.org/wiki/Electric_Dylan_controversy

And I would argue Radiohead, one of the biggest rock bands of the world as of the late 90s effectively ditching their guitars to go full Warp Records IDM for Kid A to critical AND commercial acclaim is a similar signifier. Guitars are there, but they are in supportive roles. And to be honest, many of the synths being used are basically guitar parts in sound and in songwriting use. You’ve got bands like Death Grips who basically updated Rage Against The Machine’s playbook around electronic production, and I remember reading a review for an electronic duo called Fuck Buttons “the best rock album of the year” lol.

https://www.youtube.com/watch?v=FggHwHnoz8U

Traditional guitar based rock is still around though; as the traditional music biz becomes ‘flatter’ it seems that the working acts that survive tend to be the ones who are able to tour and put on a good show, and that is still the realm of live drums, bass and guitar.



*Funny enough technology has made it easier to use guitars too. In the past you used to have to have 500 pound amps and a plethroa of pedals and gear to form your sound...now many mid tier to huge rock acts simply get shoe box sized amp simulators and plug it directly into the venue's PA system.


**While so-so blues rock bands like the Black Keys are making bank off that lane that White Stripes made, imho their real contribution to rock music was bringing 60’s garage rock bands back into style which seems to be where the most interesting hard hitting guitar work seems to be happening...the niche that used to be punk rock in the 80's and 90's is basically that genre now.