The points on which I object are that simplistic 10x idea (how does that even operate over time, since viruses grow exponentially?)
And that countries in Asia-Pacific mostly avoided deaths because it was a weaker strain; rather than effective crisis response.

(Nature paper below concerns data until 3rd of July)

So the first aspect is case fatality/mortality rate.
This figure is a decent summary of that topic: https://www.nature.com/articles/s10038-020-0808-9/figures/1

There are roughly 3 genetic clusters of the virus. If you look at the worst performing countries (highest points) we can see that the red/blue clusters (that contain G614) are about 3x more deadly. (or 2x when comparing means instead)
More important is the amount of spread within those clusters. Within the red cluster for example, there is one country with about 15% case fatality rate, and another around 0%.
The point is, the virulence of it hardly even matters, because countries that do well completely wreck this virus anyway.

As you can see from that figure, the viral gene profile of Australia is mostly the same as the USA. (except that Australia has encountered a somewhat greater variety of mutations)
And the prevailing blue cluster in the USA is clearly milder than the red one in Brazil, Italy, or Iceland.

You're not entirely wrong about the bigger picture, it is just extremely misleading to use that 10x number, and to ignore the fact that variation between countries is so much larger than between strains.
This even clearer in this next figure from the same paper: https://www.nature.com/articles/s10038-020-0808-9/figures/2

The second part is the total number of infections that are allowed to happen, that one would expect to increase with contagion.

And to that end: https://www.cell.com/cell/fulltext/S0092-8674(20)30820-5 (with data until March 20th)

It shows that G614 (and total 3 out of 4 mutations define the 'G clade') originated in China; but that 4th 'G clade' mutation likely first occurred in Italy. (not that it really matters, these mutations were basically inevitable)
This 'G clade' soon dominates over the 'D clade'. There likely is increased contagion/transmissibility, but there are multiple mechanisms by which relative fitness could operate.
If it were possible to conclude increased contagion from the available data, that paper would already be doing so with great enthusiasm.

And again this paper shows that "G clade" exists in both Australia and USA in comparable ratios at the same time.
D614 initially dominated in both, but was soon displaced by G614.

And yet Australia did okayish, while the USA did not.
There are many ways to try and explain that; but viral strain (while I cannot entirely rule it out here) seems unlikely to be that significant.

I mean really, do people forget the insane lengths that China went to?
Who cares if they were even spraying disinfectant; it could have been straight up steam machines and saved thousands of lives just by scaring the shit out of people.
https://www.youtube.com/watch?v=pBlV4tTRxFY
https://www.youtube.com/watch?v=vLdwCdyiDCw
https://www.youtube.com/watch?v=t_paSG16bWg
https://www.youtube.com/watch?v=oWqCUpKTUa8

Sorry, I don't know when to quit.
And have too much time on my hands apparently.