Its post rock as it takes the ideas of rock music and deconstructs them and then reconstructs them, using certain musical ideas and devices. For example it may take a piece of music that could be considered an intro and they would stretch it out over an entire song, its post modern and I think thats where the name originates from. It takes the cliches of rock and roll and subverts them. Its an intelligent evolution of the genre and i dont think instrumental rock encompasses what these bands are trying to do.
It doesn't do all that. It's instrumental rock, that's all.
What people like yourself (not saying you are specifically trying to do this) are trying to do with these labels is make themselves sound like they know what they're talking about.
GYBE! are instrumental rock, that's all. Nothing 'After' about them.
Post-rock is a fake label because how can there be anything after it? It's always in current existance.
It's rock, not post-rock. Just instrumental rock. Post means after. So for example, when anyone says post-grunge, they're referring to any music after grunge. Including pop.
For you to discount that this is a postmodern style of music is just ridiculous and pedantic, clearly you dont understand the concept of post-modernism.
Postmodern does not singularly refer to music that comes after other music, did you read the definition. It is about consciously mixing up certain elements and devices established by prior generations of musicians.
But things like the Yardbirds and Led Zeppelin were most definitely post modern in relation to their time in history, they took the basic ideas of the blues and built upon them,you cannot say that Blind Lemon Jefferson sounds the same as Black Dog or When the Levee Breaks, but they were most definitely influenced by Jefferson. They were not labeled as Post Rock at the time as theories of Post modernism arose after this period.
And almost every art form cannot avoid post modernism it is the very basis of artistic evolution