If I had to narrow the Internet down to two things (not including cats and porn), it would be that 1) no one in the history of time has apparently ever had a valid analogy (at least in the eyes of an opponent) and 2) people misunderstand arguments all the time. I want to focus on the second thing.
Often someone will put forth an argument that focuses on factor x, but the objection will inevitably be on factor y. There’s something about being able to see through one’s bias to the frickin’ point that people can’t seem to do. For instance, I recall a philosophy course I once took where the professor used abortion access as an example for one thing or another. The point, as anyone ought to be able to tell, was access. In this instance, abortion wasn’t the focus. Yet, another student predictably tried to make the issue about the rightness or wrongness of abortion. It took no fewer than 3 times for the professor to get the student back on track. And he wasn’t a dumb kid, either.
This is what we often see on the Internet. Even when an issue is explained with utter clarity, a person’s bias just will not allow for a fair understanding. It’s practically willful ignorance; it’s actually amazingly frustrating. Here are just 3 issues I’ve noticed in my debating/discussion days online:
1. Circumcision protects against HIV transmission between heterosexual couples. The usual objection to this is on ethical grounds. This is an invalid objection. The science is the science. You don’t have to like it, but you don’t get to deny it because it’s inconvenient for your ethical stance.
2. Spanking is an unethical practice. The usual objection to this is that people don’t want to raise brats. This is an invalid objection. Aside from the fact that spanked and unspanked children turn out about the same (thus making the objection a troll objection in the first place), the argument is an ethical one. (This is the reverse of the circumcision argument.) Spanking could result in ideal citizens that make the world a better place, but that doesn’t make it right. Disagree that spanking is unethical if you want, but do so by arguing ethics, not efficacy.
3. Talking to the police will not benefit you. The usual objection is that most police aren’t bad people. This is an invalid objection. The reason talking to the police is a bad idea is because anything you say can and will be used against you in court, even if you’re innocent. It doesn’t matter if we’re talking about the best of police or the worst of police. This is about how the justice system works, not any individuals within the system. Indeed, don’t talk to any city, county, state, or federal investigators. That includes street cops, detectives, district attorneys, Congress, or any other person working in an official capacity for the justice system. Your freedom cannot be benefited from talking to the police more than it will from keeping quiet.
For the Sake of Science 
Regarding #1, the ethical objection is not to “Circumcision protects against HIV transmission between heterosexual couples” but is rather to “Circumcision protects against HIV transmission between heterosexual couples so we should circumcise all the boys” and is valid, particularly when the science (as in this case) is not actually as clear as it’s being presented.
What I’ve found time and time again is that the anti-circumcision crowd will refuse to discuss the science of the matter. For many of them, it doesn’t matter what benefits there are to circumcision. They simply care about the ethical side of the debate. And that’s fine – so long as that’s the side being discussed.
1. It still is not a valid objection, even if the science is weak. That’s like saying an objection to string theory that is based in theology is particularly valid because string theory is not yet a very strong science. The theology still says nothing of string theory.
2. The science is very strong on HIV prevention and circumcision. Most studies find a reduction in transmission somewhere around 45%, going upwards of close to 70%, and rarely if ever dipping below 33%. In fact, the debate has swung from “is it effective?” to “why is it effective?”
Castration would also protect against HIV transmission. Therefore, all boys should be castrated. Whoops.
Apples and oranges. Circumcision has no negative health consequences.
Not that such an objection has anything to do with the science argument.
Not that the science argument has anything to do with whether circumcision is a good idea…. which was my point.