That one makes perfect sense to me, as if it said like "1 second ago", this would almost always be a wrong statement due to differing clocks, and the time taken to render and send you the page.

If the time is static on the page rather than dynamically updating in JS, for such small intervals it'll already be out of date by the time you scroll down to read it. But dynamically updating timestamps is irritating because it causes the content to "animate", and that movement catches the eye for no good reason, since nothing is really changing with the content (Reddit does this).

Due to clock skews you can even have the event come from slightly in the future, and marking that accurately like "2 seconds from now" would be even more confusing.

"just now" solves all these issues

See: https://news.ycombinator.com/item?id=37881456