I always thought the point of lazy loading is to save the company serving the on bandwidth costs. AFAIK it's never been a good user experience scrolling down and then having to wait for images to load.
That's exactly what it's for. Modern browsers already optimize request order to grab above-the-fold stuff first. Below-the-fold images are loaded eagerly, but only after that.
Of course, they aren't perfect at this, because in general figuring out what's above or near the fold is equivalent to the halting problem (thanks, Javascript!). They do it well enough for the typical case, though.
Given prolific use of CDNs and the abundance of cheap bandwidth, saving the transfer of some images isn't as much as a concern as it may have been once upon a non-cloud point in time.
However, if 40-50% of your visitors bounce because your page takes 5s to load[0][1] due to your longform photo essay hammering the user's 4G connection with a bunch of images they won't even see 5 minutes into scrolling down, this is a real concern. Lazy loading shines in these moments.
In any decent implementation, the lazy loaded images should be loaded before you scroll to them, unless you're jumping halfway down a page. They don't just load what's visible, but also the next section that it's expected you'll scroll to.
Also depends on the skill of the maintainer. Some unskilled maintainers joyfully upload high res unoptimized images (esp if the cms also doesn’t have constrains in place)
