In reality, it seems that people have just settled on a response time that's acceptable and devs try to stay within that window in most cases.
More specifically, every time CPUs or browsers get better, publishers look at their metrics and go "Oh! PLT at 95th percentile is down! Great, now we can add more trackers while still hitting our perf target!" and so the gain is immediately gobbled up -- we're in a Red Queen Race and websites will never get faster. I cannot wait for the adtech ecosystem to collapse, what a godawful waste of resources this is.
I've heard that airplane fuel is becoming prohibitively expensive and consumer demand for flights is relatively elastic, so this (and all the other ways they behave miserly) are attempts to remain solvent without drastically raising prices. I feel somewhat sympathetic to that argument (if it's actually true), but it seems like that should be a signal for technology to step in and innovate around the problem rather than attempting to blunder through with more advertisements.
Why not verify what you've heard? Kerosene prices have actually fallen dramatically from just a few years ago.
https://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=E...