Whenever I talk to a friend about post-rock they say they don't think it counts as music, is this a common thing?

Basically the title, I have a friend who i talk to a lot about music, and when we discuss albums we've listened to and I mention that I've listened to a post rock album, they say that they think these albums are just noise and not really music. Is this a thing that has happened to any of you, and if so, do you have any idea as to if i could convince them otherwise? Sorry if this post doesn't fit the subreddit, just curious about this.

UPDATE: I asked my friend why they said this and turns out, it was a miscommunication based on each of us having imperfect information. We have come to a greater understanding of eachothers definitions of music and personal tastes after this. This is still a very interesting discussion in the comments, I just wanted to update Y'all because i don't like leaving people with the wrong ideas.