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.

0. https://royal.pingdom.com/page-load-time-really-affect-bounc...

1. https://developers.google.com/web/fundamentals/performance/r...