Oh yes. Party discipline is still a considerable force in proportional governments, but it's much less powerful than in two-party dictatorships, because absolute majorities in the parliament are the exception, not the norm. You have to be able to form coalitions with different-minded people if you want to form a government. And you usually have to find a compromise with at least one other party leadership before you can get a specific law approved in the parliament. This hurdle works wonders in eliminating insane ideas and politicians from the political process.

In my experience with the German system no one except the populists even likes absolute majorities, because they give far too much political power to one political party, with all the ugly side effects. I makes shooting down stupid and harmful initiatives unnecessarily hard, it allows crazy, half-educated backbenchers without diplomatic or intellectual skill to creep into strategic key positions, it enables sprawling corruption and cronyism.