Open any random site without an ad blocker and it is clear that nobody cares about well optimized sites.
Very likely the site is well optimized. It's optimized for search engines, which is why we found the site in the first place, which is in turn the reason I said "very likely" in the first sentence: we come upon web sites not truly randomly but because someone optimized them for search ranking. It also appears from your "without an ad blocker" that the site may be optimized for ad revenue, monetizing our visit as much as possible. There's probably optimization of tracking you in order to support those ads, too.
What you're complaining about is that the site is not optimized for your reading enjoyment. The site is probably quite well optimized, but your reading enjoyment was not one of the optimizer's priorities. I think we agree about how annoying that is and how prevalent, so the news that new typographical features are coming seems to me like good news for those of us who would appreciate more sites that prioritize us the readers over other possible optimization strategies.
I want to believe you. I just can't bring myself to agree, anymore. Most sites are flat out not optimized, at all. Worse, many of them have instrumentation buckled on to interface with several different analytics tools.
And to be clear, most sites flat out don't need to be optimized. Laying out the content of a single site's page is not something that needs a ton of effort put into it. At least, not a ton in comparison to the power of most machines, nowadays.
This is why, if I open up GMail in the inspector tab, I see upwards of 500+ requests in less than 10 seconds. All to load my inbox, which is almost certainly less than the 5 megs that has been transferred. And I'd assume GMail has to be one of the more optimized sites out there.
Now, to your point, I do think a lot of the discussion around web technologies is akin to low level assembly discussions. The markup and script layout of most sites is optimized for development of the site and the creation of the content far more than it is for display. That we have moved to "webpack" tricks to optimize rendering speaks to that.
The developer in such a case is only allowed to care as much as the PM.