Well, that's the nature of language and on top of it, ideology.
We use reductions such as "left wing" and "right wing" to communicate efficiently and then we pick them apart to communicate in detail.
I agree it's pernicious, and there are plenty of idiots out there discussing politics like it's football, but it's also necessary, don't you think?
Going a bit beyond that, though, I'm not always convinced there is much value in calls for more open-minded debate. A lot of things that are still widely and fruitlessly debated have been well and truly decided at the intellectual level for ages.
The high value set on this endlessly talking things through is arguably a symptom and a rationalisation of the attenuation of public influence over political outcomes. We act as if we are "debating" climate change, but really what's happening is the necessary action to limit global warming is being forestalled because it is so inconvenient to powerful interests.
Meanwhile, many huge economic transformations continue apace despite their premises being far more in question.
