The recent literature on immersive hasn't really defined the word. The assumption your correspondent has made is to say that immersive-ness is to get so lost in the moment of the activity that all else ceases to matter, which suggests that immersive-ness is up there with authentic. The Carpenter immersed in his work, with no care for the world beyond his or her hammer and chisel. Some, probably in the past, have considered this sense of immersive-ness as the gold standard around which society is best arranged. But I don't think that's what the literature means by immersive.
The literature goes on to argue that while there might have been a time when
opportunities to immerse were limited to something like reading a book more
recent innovations and technologies available to sections of the earth's people
have resulted in a increased arena of immersion with a consequent dramatic
shrinking of attention span. Better perhaps to put the whole problem into in the
perspective of Pong, a computer game which some years ago was very much the rage
for those of us unallied to any sort of useful activity. Yes indeed it's a long
journey traveled since the pen and inks of an illustrated manuscript.