Why do some only post what supports their lopsided view - isn't that lying by exclusion?

The raving lunatics on here who post questions which are not backed-up with facts, yes. People who support a way of thinking such as being either for or against abortion, not so much, even though it is legal I can see where some people would have a problem. If you can back up what you say with accurate facts, no, even if that is all the person ever posts. I do not like the republican style of politics, at least today's style and that is mostly what I post about but I don't say things that aren't true, and truth be told, I don't really care for either party it's why I have been an Independent for more than a dozen years.