The web has no APIs for this. Instead laziness is tacked on through JS, and invariably breaks find, scrolling, etc. Try scrolling to the bottom of your Chrome history: the scrollbar jumps and it's often not clear if/when you reach the bottom.
iOS has scrollbar jumps unless you know the rendered height of every list item and the complete count of list items in advance (which is why Chrome jumps, it doesn't know the entire length of your web history, it's loading it in batches)
Funnily enough, _SwiftUI doesn't support lazy table views_. Seriously. It's nuts.
I do not agree that the JS implementations have "solved" lazy tables: they're all invariably broken. For example if you hit cmd-A to Select All, Chrome history just selects what is faulted in. If you scroll down eventually you find unselected items. Safari doesn't have this problem and the main reason is its use of native tables instead of web tables.
I agree this is a big hole in SwiftUI as well. A lazy table requires cooperation between the framework and the app, which is an awkward fit for declarative UI frameworks like SwiftUI and the web.
It's not at all representative of the experience of using Gmail, Ymail, Hotmail. The web requires heroics to get quality.