FWIW, I don't know if I'd draw the lines in exactly the same place, but I think that is explicitly correct, as in, I saw a blog comparing the UK system to the Dutch PR system, and the plethora of parties make a lot more sense if you think of them as "the xenophobic right-wing of this party", "the social-liberal part of this party", etc.

And I think (at least notionally) that issues that in a PR system would be resolved by parties negotiating with each other to decide who can form a government, will be resolved within one party by voting on a leader, and the leader needing to forge a compromise between the two tendencies in that party. That has less granularity -- it's a lot lot easier for compromise between two tendencies within one party than for (eg) right-labour and left-conservative to form an alliance. But there is _some_ effect whereby issues which are not broken down by party lines get settled, even though it's rather bad.