That's assuming a level of critical thinking that exists on HN and a few other forums but isn't really common to the general public.
Most people go into a new topic or new issue area with a basically neutral stance. They aren't looking to disprove the argument, nor do they even view it as an argument. Rather, they're thinking "OK, show me how this is relevant - tie it into my life and how it affects me, then I'll make up my mind based on my feelings afterwards" (in a far more subconscious way - basically nobody actually goes through these thoughts consciously). Analogies are your chance to do that. Get the right one and people associate your issue with something they already hold a positive position on. Get the wrong one and they just ignore you.
Or bad actors can use analogies to mislead people. Or a neutral actor erroneously uses them and the result is still misinformed people. My opinion is analogies do more harm than good, at best wasting people's time, and at worst, resulting in people coming to the wrong conclusions.
People should be educated the rhetorical mechanism they are using doesn't do what they think it does, though. It's part of developing critical thinking skills. It would help people not get taken advantage of, too.
In this case the problem is constructing poor models and using them to understand the world; it doesn't have to be used to intentionally mislead, people often can use analogies to explain things to themselves and get it wrong.
It's not without it's uses as a technique but you have to make sure the model the analogy constructs is, well, actually analogous to the situation you are modeling.
Most people go into a new topic or new issue area with a basically neutral stance. They aren't looking to disprove the argument, nor do they even view it as an argument. Rather, they're thinking "OK, show me how this is relevant - tie it into my life and how it affects me, then I'll make up my mind based on my feelings afterwards" (in a far more subconscious way - basically nobody actually goes through these thoughts consciously). Analogies are your chance to do that. Get the right one and people associate your issue with something they already hold a positive position on. Get the wrong one and they just ignore you.