It feels like this has been an issue for some time now with the internet ballooning in how resource heavy it is despite many websites not becoming all that more functional. It's the reason there is a meme of people being surprised that their browser tab is taking up so much ram. I mean yeah that news website may function similarly to how it did 10 years ago, but that tiny thumbnail is technically autoplaying a 1080p video, and despite being zoomed out in frame the photos uploaded in the background and thumbnails are also fairly large and high res even before you click on them, and there are countless other things running in the background that just arent worth it.

There was a period in the late 00s and early to mid 10s where the rise of the smart phones delayed this trend and forced developers to reconsider more minimal global experience. Flash was killed off and things got lighter weight and the new media rich features were better optimized for performance.

I think it's also not just that the developers tend to have better devices as much as it's a result of time and energy and resources put towards building software. Its similar to videogames. In the old days to save on resources a 2d game might use a single texture tile that could be mirrored, rotated, or color swapped so that precious ram space can be spared. Once the baseline or average hits a certain point(or a new console gen appears) a lot of that "optimization" goes away because it's not needed. Sometimes it's obvious and we're better for it like clouds no longer having to play double duty as bushes, but othertimes it means that we move onto something that technically looks marginally better but absolutely leaves a good chunk of contemporary hardware in the dust.

I think the most frustrating things about websites is that things arent that different for all the under the hood changes we get. Google maps is a lot slower in firefox than it used to be, and the android app uses more resources on mid range hardware than it used to(I'd know I remember using it on my HTC Dream/G1). Functionally I have been able to do the same things I can do now on google maps for probably more than a decade now. New technology has been introduced in the backend to make maps "better" but it is at the cost of CPU ticks and snappiness. Likewise a lot of news and article websites dont look that much different than they used to 10 years ago. Sure things are laid out differently and aesthetics change, but the navigation is fairly steady. But we have all this javascript and bandwidth sucking media autoloading and creating a slower experience. Even modern hardware can suffer from this.