Completely agreed on SOE's/quasi-SOE/s being valuable as initial investors in (riskyish?) long-term ventures---I tried to acknowledge that by saying they had been a great force for good in the Chinese economy for several decades (1978-2008, roughly) when China's infrastructure needs were insanely high. But SOE's are 25-40% of the economy (Minxin Pei and other academics seem to use 25%, Forbes and other financial articles seem to use 40%), and like 80-90% of SOE activity is infrastructure (or finance financing SOE's i.e. infrastructure), and at some point you run out of infrastructure to build, which would be the point when the initial investor in long-term infrastructure role of SOE's would stop being good and instead would be devastating (since 25-40% of your economy would now no longer be productive, or whatever portion of the SOE's wasn't needed for simple maintenance).

On the political side of things, for sure, they are a hugely valuable chip both in acquiring foreign technology, and acquiring strategic assets you could use against adversaries as you noted (for instance, shutting of Portugal's power, I mean "technical difficulties" in a dispute with the EU, or Huawei turning off Australia's 5G etc).

I'm just noting that the SOE's in that case are not economically productive, it's more like military or intelligence spending (in the sense that US military spending, DARPA and funding of new tech notwithstanding, is generally not economically productive), and I think a real acceptance of and understanding of that would greatly improve our discourse around China's economic "model." It's not some magic pill where SOE"s are magically "good" because "authoritarian" or "better-managed," they're just good at building long-term bias projects, and political economy influence operations, once you no longer need bias long-term infrastructure projects, and once adversaries stop allowing the economic influence operations, they're just massive pools of unproductive resources that your people might like to have a chance to get their hands on.