People take exception because it resembles an assembly line of sorts, and yes at it’s very worst I’d agree and it can get VERY fatigueing and irritating when a certain sound becomes this. But thats true of every genre, but as people are exposed to pop music more than yer Indie Rocks and Metals of this world people mostly associate it with Pop Music. As Pop music is always, by definition, whatevers popular right now its been stigmatised over decades of fads boiling music down to its purest elements.
But like EVERY genre there are shining examples but people dismiss them due to a pre ingrained bias. Saying its not ‘real music’ is very dismissive considering the music is often composed by very well regarded musicians. People shit on a song that takes a team of writers to make it, but in reality its no different to a band of people writing a song. Basically every argument against the merit of pop music can be countered, and often thrown back to ‘the elite’ of music.