The effect of coalitions is in political execution rather than in ideological separation. The concern here was entirely about the social impact on residents, not the political efficiency.

Coalitions can partly negate the benefit of the “spectrum”, but each member still answers to a different body of voters and going along with too many conflicting proposals would put them at risk of losing the confidence of their voters. Not differentiating from the other coalition members puts the party at risk of voters jumping ship to the others, and each party ultimately wishes to grow their own voter base.