You're right that HFT, large-scale backend, and real-time systems care deeply about performance, often with far more money at stake.
But those domains are rare. The vast majority of software development today can genuinely throw hardware or money at problems (even HFT and large backend systems). Backends are usually designed to scale horizontally, data science rents bigger GPUs, embedded gets more powerful SoCs every year. Most developers never have to think about cache lines because their users have fast machines and tolerant expectations.
Games are one of the few consumer-facing domains that can't do this. We can't mandate hardware (and attempts at doing so cost sales and attract community disgust), we can't hide latency behind async, and our users immediately notice a 5ms hitch. That creates different pressures- we're optimising for the worst case on hardware we don't control whilst most of the industry optimises for the common case on hardware they choose.
You're absolutely right that we're often ignorant of advances elsewhere. But the economic constraint is real, and it's increasingly unusual.
A browser like Chrome also rests on a rendering engine like Skia, that has been optimized to the gills, so at least performance can be theoretically fast.
Then one tries to host static files on a express webserver, and is suprised to find that a powerful computer can only serve files at 40MB/s with the CPU at 100%.
I would like to think that a 'Faustian deal' in terms of performance exists - you give up 10,50,90% of your performance in exchange for convenience.
But unfortunately experience shows there's no such thing, arbitrarily powerful hardware can be arbitrarily slow.
And as you contrast gamedev to other domains who get to hide latency, I don't think its ok that a simple 3 column gallery page takes more than 1 second to load, people merely tolerate this not enjoy it.
And ironically I find that a lot of folks end up optimizing their React layouts way more than what it'd have cost to render naively with a more efficient toolkit.
I am also not sure what advances game dev is missing out on, I guess devs are somewhat more reluctant to write awful code in the name of performance nowadays, but I'd love to hear what advances gamedev could learn from the broader software world.
The TLDR version of what I wanted to say, is I wish there was a linear performance-convenience scale, where we could pick a certain point and use techniques conforming to that, and trade two thirds of the max speed for dev experience, knowing our performance targets allow for that.
But unfortunately that's not how it works, if you choose convenience over performance, your code is going to be slow enough that users will complain, no matter what hardware you have.