Who cares about History? What matters is now and what people want now. If not, you could use that excuse "but X was always part of Y" to justify just about everything.
The reality is we don't know how many HK residents want to be independent. Ideally they could hold an independence referendum, but the Chinese government don't want that, and due to the geopolitical tensions in the world right now they're not going to take advice from Western nations.
You could make the same argument to the UK about Wales and Scotland, or Spain with Catalunia and the Basque Country. Neither government is going to let a referendum happen for quite a while.
If there was good reason to think Californians wanted this, I'd be all for it. Also, there most pressing issue is American investment in California, which isn't so much of an issue in HK.
> What if China told the USA to end the trade blockade on Cuba
Not sure what this has to do with HK, where trade and international relations are generally better than the mainland..
> we don't know how many HK residents want to be independent
and we never will because PRC don't want to know, don't want anyone to know, and make it clear that it will punish democratic support, let alone independence.
> You could make the same argument to the UK about Wales and Scotland, or Spain with Catalunia and the Basque Country
And indeed, I would. But the Spanish government isn't ripping up agreements like PRC, plus its a willing member of the EU.
China has grown large and powerful. If history matters, Hong Kong is probably part of China. If history doesn't matter, Hong Kong is part of China.
I think the real question here is what was possible for Hong Kong vs. what actually happened. Riots were maybe not the best strategy, in hindsight.
Has any strategy ever worked with the CCP?
History does matter. You cannot just invade a country, steal territory and then later say "it doesn't matter if this was once your territory, what matter is NOW and now I own it so get off my lawn".
That's just not how it works. In terms of history Hong Kong belongs to China and only in super recent history it was "taken" by the British always with the arrangement that it still belongs to China and would get handed back to China. So now that China does what is rightfully their right people act surprised, because the West hoped that if a little bit of time passes that China will stop caring but they were wrong. China took care of what was rightfully theirs and kept a tight grip over it because it saw what the West wanted to do and honestly fair play to them.