I've been a lurker on this forum for awhile and the boastful rhetoric is utterly bizarre to me. There are a couple of reasons behind it and people need to consider why it is they follow some of them.
1. Trying to be persuasive: Some people seem to think that ad hominem attacks, insults, lies (or perhaps "creative re-appropriation of former facts into a non-standard truthiness matrix") and other forms of *ahem* non-standard argumentation are going to let them prove their points best. Sadly, that's sometimes true - we have a long human history of caving to poor arguments.
Alternatively, some people use such an approach because they can't express themselves any other way. These people just need to be ignored or lightly cajoled.
To those who choose rhetoric over more reasoned exposition, all I can say is that it honestly feels better when you make a valid point without resorting to personal attacks and the like. Rational argument is a fantastically persuasive force and not using it when you are capable says to me, in some sense, that you are simply insecure about your inability to argue well and you would do yourself and everyone else a good turn to overcome that insecurity and contribute to the dialog in a better way.
2. Emotional reaction: I don't know why people have strong emotional attachments to electronics manufacturers. In many ways, this is exactly what those manufacturers want and I honestly find it kind of scary to see so many people who have bought into that mentality and are devoting their time to proselytize. These companies work for us, not the other way around. The great benefit of having your super-advanced-mega-monkey-brain is to use it for higher levels of thought, e.g. mitigating your emotional responses by stepping back and thinking about them before you type.
3. I'm just a bastard: Some people on the internet are just jerks and won't change. There are people who aren't on the internet that are jerks as well, I meet them all the time. They are probably the same people...
There are plenty of other motivations, but I'm too tired to think about them right now.