Ah, I didn’t say not ?, I said not ?.
I’m a bit thrown by this idea of subsets… Is it really applicable? And even in a situation where it were – the paintwork on a car being part of the car – just because a car had good paintwork wouldn’t make it a good car (eg. the engine might not work) and you might think a car is great even if its paintwork isn’t the best.
However… An example might be the circle of wood and stone around Mercy. It might be argued that it was a weak plot point, that the gunslinger’s motivation was insufficiently explained, and then a range of more suitable alternative strategies would have been available to him. But it’s wonderful storytelling. It does more than create the claustrophobic siege atmosphere, the imagery of the circle is very powerful, not just in giving us a visual cue for the encapsulation of the town but also in imagining the psychological effect of such a potent symbol. And it’s clever staging for the confrontations on the town’s edge. Yes, there could have been a lot of additional explanation to make the plot bomb-proof, but it wouldn’t have enhanced the story, it would have dragged. Anyway, you’ll probably disagree that this is an example of good storytelling, but I’m not trying to make the case for it, just show that it must be judged on different terms.
In the farewell segment of Angels the central plot device – that foreknowledge determines an unchangeable future – is completely violated. It is literally set in stone that Amy is not buried in the same grave as Rory, and she sees this. The future still changes. But that’s not really the problem; we’d ignore or forgive a plot hole if the story justified it. The weakness in the story is that although it has a beginning, a middle and an end, it has already had all of them by this point. Rory has been zapped back before. The Doctor couldn’t follow him back before. Yet he tried, and prevailed, and we saw that. Now, suddenly, we have exactly the same situation but words are being thrown around to rapidly explain why Rory is irretrievable this time when he wasn’t last time. It seemed an unusually threadbare moment for a Moffat story. The plot showed through, and yes, it was found wanting, but it’s the hole in the story that really mattered.