You are sacrificing your end result every time you don't spend a lifetime designing a custom processor for your application with an instruction set specific to your use case and instead have an easier time living like a normal human being.

You can go to extremes, as your preposterous mine-the-silicon-and-smelt-the-chip approach, or you can go to the sort of extremes that makes opening a news article grind my high-end phone to a halt for 20 seconds.

That news source is then bloated and unoptimized. There are also a lot of bloated and slow native apps. I don't see your point.

I think there’s a balance to be struck between developer convenience and product quality+performance. If every developer leaned to the extreme convenience we’d quickly end up with a lot of unusable software.

True, but that balance is going to be different for every application domains.

At the end of the day, one of the few metrics which really matters is the return on investment.

A lot of software can afford iterative improvements as well, so its a great idea to start off with extreme convenience and optimize as you scale.

You're sacrificing performance, not the end result. However, a lot of the performance tricks do carry over (such as object pooling for example.)

But for 99% of the web this doesn't matter at all. I'll take declarative over imperative any day if it means I can spend the saved time polishing the product instead of debugging or optimizing.

You have no idea the amount of debugging and optimizing which goes into developing a video game. Having worked on both I can say time spent debugging/optimizing is at least an order of magnitude more than for web applications. Its much worse when you're using an in-house engine as well.