I wish there was a bit of an opposite option - a "don't lazy/partially load anything" for those of us on fiber watching images pop up as we scroll past them in the page that's been open for a minute.
A little OT, and I'm not sure if iOS has this ability, but I found that while I'm traveling, if I enable Data Saver on my (Android) phone, I can easily go a couple weeks using under 500MB of cellular data. (I also hop onto public wifi whenever it's available, so being in a place with lots of that is helpful.)
My partner, who has an iPhone, and couldn't find an option like that (maybe it exists; I don't think she tried very hard to find it), blew through her 5GB of free high-speed roaming data (T-Mobile; after that you get 256kbps, essentially unusable) in 5 or 6 days on that same trip.
It turns out there's so much crap going on the background, and it's all so unnecessary for the general user experience. And I bet it saves battery too. Anything that uses Google's push notifications system still works fine and gets timely notifications, as IIRC that connection is exempt from the data-saving feature.
I've thought about leaving Data Saver on all the time, even when on my home cellular network. Should probably try it and see how it goes.
But overall, yes, it would be great if website designers didn't design as if everyone is on an unmetered gigabit link with 5ms latency...
She might have kept tapping Sync at the bottom of Photos even though iOS itself pauses it when in Low Data mode. iCloud Photos and video syncing is a data killer if you're on a holiday abroad, my wife takes hundreds of photos and videos a day, imagine what it does to data.
The tragedy here is that while some people, such as the author of TFA, go to great lengths to get from about 100 to 50 kB, others don't think twice to send me literally tens of megabytes of images, when I just want to know when a restaurant is open – on roaming data.
Resource awareness exists, but it's unfortunately very unevenly distributed.