These sort of tips are only useful in highly specific cases. It's probably not worth learning them off by heart because of how infrequently you'll end up using them. BUT, understanding how the author(s) came up with these is incredibly powerful. The combinatorial explosion of the composition of Vim features means that it's practically impossible to learn all of the commands.

That said, it's really beneficial to learn how to form these commands yourself. For instance, if you know regexes, a good chunk of the commands presented would be relatively easy to come up with yourself. Is it worth learning regexes, Vim shortcuts (basically a lot of arcane things)? Maybe, maybe not. If you spend (or plan on spending) a huge amount of time manipulating text files it's probably worthwhile. For me at least, it's much more satisfying to do most text manipulations (e.g. remove trailing whitespace) by running a concise command, than doing it manually.

For what it's worth, it's even fun to sit and think of how you can avoid doing some manual task. Vim shortcuts + regexes are a really good way of avoiding silly work.