I think it goes without saying that doing what they can to make sure that wide scale building construction is not overly tedious is something that has to happen. Arguably more so now that you can't even fall back on a laissez-faire system like in Victoria 2.
I don't necessarily disagree with your wider point, but the concept that you need to "fall back on a laisser-faire system" is extremely concerning to me. You should not be forced to adopt an economic system just for the sake of avoiding micro. Having radical Liberalism because you want to simulate a minimal State country is fine, even laudable; having radical Liberalism just because the player thinks the country is too big for them to use another economic system is about as bad as the player having to have a command economy in order to fine-tune the economy so that the country does not stagnate.
The capitalists do not make decisions with their predecessors that simulate capitalism. A pop cannot own several factories at the same time. One speaks of RNG because pop doesn't plan either. He reacts to a concrete situation with certain probabilities. There is no bad planning going on. There is no planning at all. It's just a reaction like the farmer pop's reaction. Tags, on the other hand, always match goals.
I'm not sure if we're disagreeing or anything, but my point was not that Capitalists planned or did not; my point was that Investment Pools aren't in the game because the AI is bad, but because the design team decided that this is more fun.
Also, do we know that a pop cannot own more than one company? Did any of the devs say that? I don't think it is hard to have a certain (group of) POPs have shares on the ownership of a given set of companies and receive profits from each independently.
Regarding conglomerates as tags, I'm not sure this is something that would be in theme for Victoria; while there were some powerful priivate interests in the period (Lloyd's of London, Standard Oil, Carnegie Steel, etc.) they were not national-level players like the British East India Company had been a century earlier, so it doesn't make sense to simulate them using tags. In particular, they would not have a territory, they would not have POPs (only have POPs work for them), and they would have interests spread inside one or more of other tags which represented the countries they operated in. It's too different in mechanics.