There's some suggestion, or I've heard it said, that where you have a system of first past the post, which may work badly, or where you have two dominant parties shifting back and forth in power, you would have the problem of controversial parties put in, a change in power, and those policies taken out. There's some thought that this is inefficient, with a possible cycle of build it up and rip it down, build it up and rip it down. If there was something that didn't promote the majority putting forward their agenda, and that had more of a consensus where you needed it, a consensus of the other party, that effect might be more muted.
On September 29th, 2016. See this statement in context.