@raymondcamden No reason not to, do it today!
You can even use it on header images as the heuristic of "in viewport" applies there too.
You can even dig into possibilities with https://developer.mozilla.org/en-US/docs/Web/API/HTMLImageElement/decoding while you're at it!
The decoding property of the HTMLImageElement interface provides a hint to the browser as to how it should decode the image. More specifically, whether it should wait for the image to be decoded before presenting other content updates or not.
@raymondcamden Browsers have been able to natively display text and images since the beginning. Requiring JS in order to have browser do something it already knows to do itself should be discouraged and even ridiculed.
So thumbs up for any move away from reckless JS overuse! 😃