I think that there are distinct musical styles and I think that these styles or genres or whatever we call them do most definitely have particular traits that are more often than not found within the style.
I also think alot of listeners think that way too. At just about any party or gathering I go to where there is music, people I meet or know seem to have their own gauge of what 'this' or 'that' music is. So you stick on Burning Spear and no one mistakes him for Led Zeppelin. Why ? Because he's reggae. Eddie Grant was always viewed in the UK as reggae, but not deep, strong, authentic reggae because he was often in the pop charts. Reggae heads thought he was a sell out. But he was still identified as being a reggae artist, however cod.
Blondie weren't really thought of as punk in the UK because of their 'disco' styled hits and suits. It possibly comes as a surprize to people to discover their roots in US punk long before there was a punk scene here.
But I digress. There are literally thousands of examples I can think of. But I also think the crossover element in Western popular music since the back end of the 19th century has been more significant than has been recognized in this thread. So running alongside the evolution of particular definite styles have been the thousands of artists that have crossed over, dipped into, stolen, fused and experimented with styles that they weren't at the time asscociated with. When for example, Eric Clapton covered the Wailers' "I shot the sheriff", it wasn't so much that it was thought of as rock and not reggae, more that it was a rock dude covering a song written by a reaggae artist in a way that was reggae 'flavoured'. Many UK and West Indian black people people would laugh at the notion of Clapton's version being authentic reggae because it wasn't, neither was it meant to be. But reggae flavoured, definitely. There are aspects of the song that are sufficiently different to what old Clappers had done up till then. And that caused many listeners to sit up and say, 'that's different'.
I think you get that in all genres to a greater or lesser degree.
Interestingly, rarely does one see Paul Simon's "Graceland" written of as rock or pop.
When I was learning to play the bass, people would laugh at you if you attempted to play a style in a way that didn't appear "authentic" to them. Why ? Because even at that youthful stage, people thought in terms of genre and associated particular things with particular genres. I remember discovering that some guys I used to hang around with were calling me an Uncle Tom behind my back because I liked heavy rock, pop and suchlike. And in those days (circa '81) if you were black in England, you had to be into reggae. Soul and funk were permissable. It always used to irritate the life out of me that the intros of so many reggae records showed that the guys in those bands could handle many styles and could riff and solo and blow jazzy etc but after 17 seconds would plop into dub mode for the rest of the song. Back 30 years ago, I used to wonder why they didn't stretch out. Now I know why.
Funnilly enough, right from when I first started learning to play, I was mixing up genres. Literally whatever came out was what came out. I'm still the same in that regard although I can be alot more calculating now. If a piece is ten minutes long, I don't want it to funk groove or reggae groove or rock groove or jazz groove for those ten minutes. Unless that's the way it comes out and sounds rubbish to change it up, then there are going to be changes......