1. Because it’s off topic. This is actually a completely valid reason to downvote something according to reddiquette.

2. Because there’s a particularly offensive feature of off-topic posts with regards to a woman’s appearance. This kind of devalues her as a person, and objectifies her, in a really fucked up way. We were talking about her talents, not her looks. Why the fuck does everything have to come back to her looks? Women have qualities other than their looks, and we weren’t talking about her looks, so don’t fucking force it. And don’t get me wrong — if you’re hanging with the guys, whatever, that might be a reasonable thing to talk about, just to fill the dead air, but on fucking reddit? Just don’t reply, dude.

3. Because this particular class of off-topic posts is extremely common, representing that it’s not just a few assholes who have no respect for women except for their appearance, but a huge number of men who like to go around making a point of it. And when I say a huge number, I’m not really pointing out any statistics, just that, hey, it’s obviously not just one guy going around the internet doing this all the time, it’s a bunch. So it’s a social problem.

4. Because when people *see* this kind of disrespect, it is normalized. The more assholes running around doing shit like this, the more young impressionable dumbasses on reddit are going to think it’s okay, and the further we get stuck in the above cycle. Keep in mind that there are various communities on the internet, and 4Chan and Youtube Comments probably involve a lot more of this bullshit, because that’s how those communities just happened to form.