The article sums up quite well which principles are at play here. The fun part it's suggesting (without words), is either to pick it apart and see what each part does, play around with the constants in there, or start from scratch and roll your own... (all with the Shadertoy linked below the article maybe?)
I would say most interesting texts (articles, books, school, ...) should leave stuff up to the reader's mind to figure out. That's how someone really learns. Versus pre-baked stuff like television etc.
If something does not resonate at first that's pretty normal. You could still take it apart and start investigating words or concepts that ring no bell, for example: waves, interference, demoscene, owls, Feynman.
The delta-transfer algorithm [0] is about detecting which chunks of a file differ on source and target [1], and limiting the transfer to those chunks. The savings depend on how and where they differ, and ofcourse there's tradeoffs...
You seem to be referring to the selection of candidates of files to transfer (along several possible criteria like modification time, file size or file contents using checksumming) [2]
Rsync is great. However for huge filesystems (many files and directories) with relatively less change, you'll need to think about "assisting" it somewhat (by feeding it its candidates obtained in a more efficient way, using --files-from=). For example: in a renderfarm system you would have additions of files, not really updates. Keep a list of frames that have finished rendering (in a cinematic film production this could be eg. 10h/frame), and use it to feed rsync. Otherwise you'll be spending hours for rsync to build its index (both sides) over huge filesystems, instead of transferring relatively few big and new files.
In workloads where you have many sync candidates (files) that have a majority of differing chunks, it might be worth rather disabling the delta-transfer algorithm (--whole-file) and saving on the tradeoffs.
"It was able to squeak, but not to speak. Experts and professors wrestled with it in vain. It refused to transmit one intelligible sentence." [0]
"A translation of Legat's article on Reis' invention was obtained by Thomas Edison prior to his filing his patent application on a telephone in 1877. In correspondence of 1885, Edison credits Reis as having invented "the first telephone", with the limitation that it was "only musical not articulating"." [1]
Fascinating stuff nonetheless, these inventors and their ideas... See also previous experimenters [2]
Ralph Griswold (also known for the Icon programming language [0]), started the On-Line Digital Archive of Documents on Weaving and Related Topics [1] at the time, a gem.
[0] https://www.lyx.org/
[1] https://en.wikipedia.org/wiki/WYSIWYM