You seem to not be grasping what I'm saying in the slightest. Historical foci and events need work. Content designers do that work. It's irrelevant how large content design is as a portion of overall development or what else needs work, since content design is all we're discussing. If content designers are working on alternate history, they're not working on history. Therefore, they aren't working on things that need work in favor of alternate history.
That's not being neglected, as you can no doubt tell by seeing how Japan and Germany had
both of their historical paths improved, and the historical element of playing as Japan was improved by making China more interesting. Germany is more unique, too, with MEFO bills and SS divisions - an example of how a new gameplay element (decisions and missions) made the history-based content design broader and more interesting. That, too, fit the theme of the expansion, which emphasised Japan, China, and (to a lesser degree) Germany. You can't complain that they didn't add anything for the UK or for France in an expansion not involving them. Even then, you've got small, relevant historical details like the women in the workplace decisions.
Personally, I feel Paradox has improved a lot in that regard when it comes to DLCs; there's a lot more interesting historical stuff in general added by WtT than TfV or even DoD, which I feel failed in a number of ways - particularly for India in TfV and Czechoslovakia in DoD. I don't, however, feel like this is a zero sum game like you do, but it does come to the point where the historical things I'm interested in seeing added to China - and believe me, I made a list - are almost entirely flavour decisions and events out of my own personal knowledge.
There's only so much that can be done in terms of historical additions in events, decisions (something completely new as of WtT, mind you!), and focuses. Some of it you could definitely argue is ridiculous: Switzerland has exactly 0 forts built on its borders, for example, and the invasion of Iran doesn't really exist at all right now except for a focus that never happens.
However, in cases like that, the best thing you can do is to make a suggestion of the
specific thing you'd like added, post it in the right forum, and hope. Don't make an angry point about alt-history taking over HOI4, and don't blame them for having bad priorities. Of course they won't listen to your suggestions if that's the case, that's only natural. Instead, be specific about the reasonable things you'd like to see added, especially if it pertains to an upcoming or recently released DLC. The devs aren't perfect, and while they do plenty of research and put lots of thought into the game, they can't think of everything. Making events and decisions for flavour - even focuses, in many cases - is a quick job. Make posts and threads about that rather than trying to convince Paradox their whole method of developing their own game is wrong.