Sure, fair enough. But then again those coalitions aren't generally static, but formed around circumstances, and thus don't necessarily create the same kind of blind team mentality that we see in sports for example. And the parties within the coalitions are still aware of their internal differences, they just choose to work together for a common cause, for a period of time.
That’s how it works in the U.S. as well. The political parties are made up of coalitions of voters and over time certain groups shift or change affiliation.
At least where I've voted in the US, there are rarely only two viable choices for a state or national legislature position. Some states resolve this using primaries for D/R candidates, and a few use stricter runoffs where there are frequently several D/R candidates. At least in the towns where I've lived, there were noticeable policy differences between many of these candidates within each party, although I will readily admit that I doubt this holds for most of the US. Also, it's still generally not as widely varying in views as in countries with 3+ parties (if made viable through proportional or similar voting) instead of the multiple rounds system popular in the US.
Going back to the original point someone made in this thread, I think this two-party multiple-views system in the US actually helps a bit to drive polarization. Seemingly disparate views are drawn together under a banner of [party] with an obvious (not actually clear or cohesive) enemy in the [other party].
