It's borderline-obvious

The general principle of "transform your data into a different form which standard compression algorithms can handle better" is very well known. For example, if you want to compress text that contains a lot capitalisation you might want to first transform it like this:

some lower case AND SOME UPPER CASE lower again
->
some lower case <cap>and some upper case</cap> lower again

Then apply some standard compression algorithm, which can now spot the repeated words "some" and "case". I don't know whether this transformation works in practice, but it's an obvious thing to try, and I would claim that the Courgette transformation is only slightly less obvious.