Being self-sufficient prevents you from conflict both in preventing external politics from potentially cutting off from critical supplies, and by making the potential fruits of conquest and war fairly limited. Like who is going to go to war over 5% cheaper steel? You will trade for that deal, but likely not kill. But the trading could be part of the source of the problem because it can hollow out your own native industry over enough time, or prevent native industry from being built when it can be bought cheap.
1) more economic engagement would somehow make China democratic
2) an economically integrated China would be more interested in maintaining international stability
3) WTO membership would force China to follow trade rules
Indulging in conspiracy at least allows you to pretend that the "top level" had a plan here.
It's much more comforting to think there was a positive intention for the way things turned out, and not just greed and short-sightedness.
Lots of people have written about "the cycles of empires".
This kind of psychologizing can be used to subjectively argue either case.
For example, I could say that it's much more comforting to think that current circumstances are artifacts of greedy fools rather than coordination by malevolent and powerful actors.
> that the "top level" had a plan here
You're also being somewhat reductive here. Sure, entry-level conspiracies rely on an all-powerful council with top-down authority, but there are more nuanced understandings where they can arrive out of alliances of convenience between rival factions.